diff --git a/QtGameMaker.pro b/QtGameMaker.pro
index 50b5eae..40540fd 100644
--- a/QtGameMaker.pro
+++ b/QtGameMaker.pro
@@ -11,8 +11,11 @@ HEADERS += \
     dialogs/fontpropertiesdialog.h \
     dialogs/imageeditordialog.h \
     dialogs/objectinformationdialog.h \
+    dialogs/objectpropertiesdialog.h \
     dialogs/pathpropertiesdialog.h \
+    dialogs/roompropertiesdialog.h \
     dialogs/scriptpropertiesdialog.h \
+    dialogs/timelinepropertiesdialog.h \
     futurecpp.h \
     jshighlighter.h \
     mainwindow.h \
@@ -34,8 +37,11 @@ SOURCES += main.cpp \
     dialogs/fontpropertiesdialog.cpp \
     dialogs/imageeditordialog.cpp \
     dialogs/objectinformationdialog.cpp \
+    dialogs/objectpropertiesdialog.cpp \
     dialogs/pathpropertiesdialog.cpp \
+    dialogs/roompropertiesdialog.cpp \
     dialogs/scriptpropertiesdialog.cpp \
+    dialogs/timelinepropertiesdialog.cpp \
     jshighlighter.cpp \
     mainwindow.cpp \
     projectcontainer.cpp \
@@ -55,8 +61,11 @@ FORMS += \
     dialogs/fontpropertiesdialog.ui \
     dialogs/imageeditordialog.ui \
     dialogs/objectinformationdialog.ui \
+    dialogs/objectpropertiesdialog.ui \
     dialogs/pathpropertiesdialog.ui \
+    dialogs/roompropertiesdialog.ui \
     dialogs/scriptpropertiesdialog.ui \
+    dialogs/timelinepropertiesdialog.ui \
     mainwindow.ui \
     dialogs/backgroundpropertiesdialog.ui \
     dialogs/editspritedialog.ui \
diff --git a/dialogs/backgroundpropertiesdialog.cpp b/dialogs/backgroundpropertiesdialog.cpp
index 78ce2a8..3824188 100644
--- a/dialogs/backgroundpropertiesdialog.cpp
+++ b/dialogs/backgroundpropertiesdialog.cpp
@@ -51,7 +51,7 @@ void BackgroundPropertiesDialog::accept()
 {
     if (m_background.name != m_ui->lineEditName->text())
     {
-        if (!m_projectModel.renameBackground(m_background, m_ui->lineEditName->text()))
+        if (!m_projectModel.rename<Background>(m_background, m_ui->lineEditName->text()))
         {
             QMessageBox::critical(this, tr("Renaming Background failed!"), tr("Renaming Background failed!"));
             return;
diff --git a/dialogs/fontpropertiesdialog.cpp b/dialogs/fontpropertiesdialog.cpp
index c2de8e0..22ba06f 100644
--- a/dialogs/fontpropertiesdialog.cpp
+++ b/dialogs/fontpropertiesdialog.cpp
@@ -66,7 +66,7 @@ void FontPropertiesDialog::accept()
 {
     if (m_font.name != m_ui->lineEditName->text())
     {
-        if (!m_projectModel.renameFont(m_font, m_ui->lineEditName->text()))
+        if (!m_projectModel.rename<Font>(m_font, m_ui->lineEditName->text()))
         {
             QMessageBox::critical(this, tr("Renaming Font failed!"), tr("Renaming Font failed!"));
             return;
diff --git a/dialogs/objectpropertiesdialog.cpp b/dialogs/objectpropertiesdialog.cpp
new file mode 100644
index 0000000..5c34295
--- /dev/null
+++ b/dialogs/objectpropertiesdialog.cpp
@@ -0,0 +1,11 @@
+#include "objectpropertiesdialog.h"
+#include "ui_objectpropertiesdialog.h"
+
+ObjectPropertiesDialog::ObjectPropertiesDialog(Object &object, ProjectTreeModel &projectModel, QWidget *parent) :
+    QDialog{parent},
+    m_ui{std::make_unique<Ui::ObjectPropertiesDialog>()}
+{
+    m_ui->setupUi(this);
+}
+
+ObjectPropertiesDialog::~ObjectPropertiesDialog() = default;
diff --git a/dialogs/objectpropertiesdialog.h b/dialogs/objectpropertiesdialog.h
new file mode 100644
index 0000000..be33e33
--- /dev/null
+++ b/dialogs/objectpropertiesdialog.h
@@ -0,0 +1,21 @@
+#pragma once
+
+#include <QDialog>
+
+#include <memory>
+
+namespace Ui { class ObjectPropertiesDialog; }
+struct Object;
+class ProjectTreeModel;
+
+class ObjectPropertiesDialog : public QDialog
+{
+    Q_OBJECT
+
+public:
+    explicit ObjectPropertiesDialog(Object &object, ProjectTreeModel &projectModel, QWidget *parent = nullptr);
+    ~ObjectPropertiesDialog();
+
+private:
+    const std::unique_ptr<Ui::ObjectPropertiesDialog> m_ui;
+};
diff --git a/dialogs/objectpropertiesdialog.ui b/dialogs/objectpropertiesdialog.ui
new file mode 100644
index 0000000..139e94c
--- /dev/null
+++ b/dialogs/objectpropertiesdialog.ui
@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>ObjectPropertiesDialog</class>
+ <widget class="QDialog" name="ObjectPropertiesDialog">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>400</width>
+    <height>300</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>Object Properties</string>
+  </property>
+  <property name="windowIcon">
+   <iconset resource="../resources.qrc">
+    <normaloff>:/qtgameengine/icons/object-file.png</normaloff>:/qtgameengine/icons/object-file.png</iconset>
+  </property>
+ </widget>
+ <resources>
+  <include location="../resources.qrc"/>
+ </resources>
+ <connections/>
+</ui>
diff --git a/dialogs/pathpropertiesdialog.cpp b/dialogs/pathpropertiesdialog.cpp
index b7d9e27..20e40df 100644
--- a/dialogs/pathpropertiesdialog.cpp
+++ b/dialogs/pathpropertiesdialog.cpp
@@ -55,7 +55,7 @@ void PathPropertiesDialog::accept()
 {
     if (m_path.name != m_ui->lineEditName->text())
     {
-        if (!m_projectModel.renamePath(m_path, m_ui->lineEditName->text()))
+        if (!m_projectModel.rename<Path>(m_path, m_ui->lineEditName->text()))
         {
             QMessageBox::critical(this, tr("Renaming Path failed!"), tr("Renaming Path failed!"));
             return;
diff --git a/dialogs/roompropertiesdialog.cpp b/dialogs/roompropertiesdialog.cpp
new file mode 100644
index 0000000..20a72b6
--- /dev/null
+++ b/dialogs/roompropertiesdialog.cpp
@@ -0,0 +1,11 @@
+#include "roompropertiesdialog.h"
+#include "ui_roompropertiesdialog.h"
+
+RoomPropertiesDialog::RoomPropertiesDialog(Room &room, ProjectTreeModel &projectModel, QWidget *parent) :
+    QDialog{parent},
+    m_ui{std::make_unique<Ui::RoomPropertiesDialog>()}
+{
+    m_ui->setupUi(this);
+}
+
+RoomPropertiesDialog::~RoomPropertiesDialog() = default;
diff --git a/dialogs/roompropertiesdialog.h b/dialogs/roompropertiesdialog.h
new file mode 100644
index 0000000..4799276
--- /dev/null
+++ b/dialogs/roompropertiesdialog.h
@@ -0,0 +1,21 @@
+#pragma once
+
+#include <QDialog>
+
+#include <memory>
+
+namespace Ui { class RoomPropertiesDialog; }
+struct Room;
+class ProjectTreeModel;
+
+class RoomPropertiesDialog : public QDialog
+{
+    Q_OBJECT
+
+public:
+    explicit RoomPropertiesDialog(Room &room, ProjectTreeModel &projectModel, QWidget *parent = nullptr);
+    ~RoomPropertiesDialog();
+
+private:
+    const std::unique_ptr<Ui::RoomPropertiesDialog> m_ui;
+};
diff --git a/dialogs/roompropertiesdialog.ui b/dialogs/roompropertiesdialog.ui
new file mode 100644
index 0000000..7c3f317
--- /dev/null
+++ b/dialogs/roompropertiesdialog.ui
@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>RoomPropertiesDialog</class>
+ <widget class="QDialog" name="RoomPropertiesDialog">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>400</width>
+    <height>300</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>Room Properties</string>
+  </property>
+  <property name="windowIcon">
+   <iconset resource="../resources.qrc">
+    <normaloff>:/qtgameengine/icons/room-file.png</normaloff>:/qtgameengine/icons/room-file.png</iconset>
+  </property>
+ </widget>
+ <resources>
+  <include location="../resources.qrc"/>
+ </resources>
+ <connections/>
+</ui>
diff --git a/dialogs/scriptpropertiesdialog.cpp b/dialogs/scriptpropertiesdialog.cpp
index b63baef..00537a1 100644
--- a/dialogs/scriptpropertiesdialog.cpp
+++ b/dialogs/scriptpropertiesdialog.cpp
@@ -76,7 +76,7 @@ void ScriptPropertiesDialog::accept()
 {
     if (m_script.name != m_lineEditName->text())
     {
-        if (!m_projectModel.renameScript(m_script, m_lineEditName->text()))
+        if (!m_projectModel.rename<Script>(m_script, m_lineEditName->text()))
         {
             QMessageBox::critical(this, tr("Renaming Script failed!"), tr("Renaming Script failed!"));
             return;
diff --git a/dialogs/soundpropertiesdialog.cpp b/dialogs/soundpropertiesdialog.cpp
index 32d5189..c6276d5 100644
--- a/dialogs/soundpropertiesdialog.cpp
+++ b/dialogs/soundpropertiesdialog.cpp
@@ -90,7 +90,7 @@ void SoundPropertiesDialog::accept()
 {
     if (m_sound.name != m_ui->lineEditName->text())
     {
-        if (!m_projectModel.renameSound(m_sound, m_ui->lineEditName->text()))
+        if (!m_projectModel.rename<Sound>(m_sound, m_ui->lineEditName->text()))
         {
             QMessageBox::critical(this, tr("Renaming Sound failed!"), tr("Renaming Sound failed!"));
             return;
diff --git a/dialogs/spritepropertiesdialog.cpp b/dialogs/spritepropertiesdialog.cpp
index 58f20d5..a499345 100644
--- a/dialogs/spritepropertiesdialog.cpp
+++ b/dialogs/spritepropertiesdialog.cpp
@@ -63,7 +63,7 @@ void SpritePropertiesDialog::accept()
 {
     if (m_sprite.name != m_ui->lineEditName->text())
     {
-        if (!m_projectModel.renameSprite(m_sprite, m_ui->lineEditName->text()))
+        if (!m_projectModel.rename<Sprite>(m_sprite, m_ui->lineEditName->text()))
         {
             QMessageBox::critical(this, tr("Renaming Sprite failed!"), tr("Renaming Sprite failed!"));
             return;
diff --git a/dialogs/timelinepropertiesdialog.cpp b/dialogs/timelinepropertiesdialog.cpp
new file mode 100644
index 0000000..1d93c44
--- /dev/null
+++ b/dialogs/timelinepropertiesdialog.cpp
@@ -0,0 +1,11 @@
+#include "timelinepropertiesdialog.h"
+#include "ui_timelinepropertiesdialog.h"
+
+TimeLinePropertiesDialog::TimeLinePropertiesDialog(TimeLine &timeLine, ProjectTreeModel &projectModel, QWidget *parent) :
+    QDialog{parent},
+    m_ui{std::make_unique<Ui::TimeLinePropertiesDialog>()}
+{
+    m_ui->setupUi(this);
+}
+
+TimeLinePropertiesDialog::~TimeLinePropertiesDialog() = default;
diff --git a/dialogs/timelinepropertiesdialog.h b/dialogs/timelinepropertiesdialog.h
new file mode 100644
index 0000000..743ffb4
--- /dev/null
+++ b/dialogs/timelinepropertiesdialog.h
@@ -0,0 +1,21 @@
+#pragma once
+
+#include <QDialog>
+
+#include <memory>
+
+namespace Ui { class TimeLinePropertiesDialog; }
+struct TimeLine;
+class ProjectTreeModel;
+
+class TimeLinePropertiesDialog : public QDialog
+{
+    Q_OBJECT
+
+public:
+    explicit TimeLinePropertiesDialog(TimeLine &timeLine, ProjectTreeModel &projectModel, QWidget *parent = nullptr);
+    ~TimeLinePropertiesDialog();
+
+private:
+    const std::unique_ptr<Ui::TimeLinePropertiesDialog> m_ui;
+};
diff --git a/dialogs/timelinepropertiesdialog.ui b/dialogs/timelinepropertiesdialog.ui
new file mode 100644
index 0000000..8fcedd1
--- /dev/null
+++ b/dialogs/timelinepropertiesdialog.ui
@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>TimeLinePropertiesDialog</class>
+ <widget class="QDialog" name="TimeLinePropertiesDialog">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>400</width>
+    <height>300</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>Time Line Properties</string>
+  </property>
+  <property name="windowIcon">
+   <iconset resource="../resources.qrc">
+    <normaloff>:/qtgameengine/icons/timeline-file.png</normaloff>:/qtgameengine/icons/timeline-file.png</iconset>
+  </property>
+ </widget>
+ <resources>
+  <include location="../resources.qrc"/>
+ </resources>
+ <connections/>
+</ui>
diff --git a/icons/room-file.png b/icons/room-file.png
new file mode 100644
index 0000000..1c8cf50
Binary files /dev/null and b/icons/room-file.png differ
diff --git a/icons/timeline-file.png b/icons/timeline-file.png
new file mode 100644
index 0000000..07698c0
Binary files /dev/null and b/icons/timeline-file.png differ
diff --git a/mainwindow.cpp b/mainwindow.cpp
index 9a0dd62..854d3d4 100644
--- a/mainwindow.cpp
+++ b/mainwindow.cpp
@@ -14,12 +14,29 @@
 #include "dialogs/pathpropertiesdialog.h"
 #include "dialogs/scriptpropertiesdialog.h"
 #include "dialogs/fontpropertiesdialog.h"
+#include "dialogs/timelinepropertiesdialog.h"
+#include "dialogs/objectpropertiesdialog.h"
+#include "dialogs/roompropertiesdialog.h"
 #include "dialogs/preferencesdialog.h"
 #include "dialogs/gameinformationdialog.h"
 #include "dialogs/globalgamesettingsdialog.h"
 #include "dialogs/extensionpackagesdialog.h"
 #include "dialogs/objectinformationdialog.h"
 
+namespace {
+template<typename T> struct PropertiesDialogForDetail;
+template<> struct PropertiesDialogForDetail<Sprite> { using Type = SpritePropertiesDialog; };
+template<> struct PropertiesDialogForDetail<Sound> { using Type = SoundPropertiesDialog; };
+template<> struct PropertiesDialogForDetail<Background> { using Type = BackgroundPropertiesDialog; };
+template<> struct PropertiesDialogForDetail<Path> { using Type = PathPropertiesDialog; };
+template<> struct PropertiesDialogForDetail<Script> { using Type = ScriptPropertiesDialog; };
+template<> struct PropertiesDialogForDetail<Font> { using Type = FontPropertiesDialog; };
+template<> struct PropertiesDialogForDetail<TimeLine> { using Type = TimeLinePropertiesDialog; };
+template<> struct PropertiesDialogForDetail<Object> { using Type = ObjectPropertiesDialog; };
+template<> struct PropertiesDialogForDetail<Room> { using Type = RoomPropertiesDialog; };
+template<typename T> using PropertiesDialogFor = typename PropertiesDialogForDetail<T>::Type;
+}
+
 MainWindow::MainWindow(QWidget *parent) :
     QMainWindow{parent},
     m_ui{std::make_unique<Ui::MainWindow>()},
@@ -78,12 +95,15 @@ MainWindow::MainWindow(QWidget *parent) :
     connect(m_ui->actionProperties, &QAction::triggered, this, &MainWindow::showProperties);
     connect(m_ui->actionFindResource, &QAction::triggered, this, &MainWindow::findResource);
     connect(m_ui->actionShowObjectInformation, &QAction::triggered, this, &MainWindow::showObjectInformation);
-    connect(m_ui->actionCreateSprite, &QAction::triggered, this, &MainWindow::createSprite);
-    connect(m_ui->actionCreateSound, &QAction::triggered, this, &MainWindow::createSound);
-    connect(m_ui->actionCreateBackground, &QAction::triggered, this, &MainWindow::createBackground);
-    connect(m_ui->actionCreatePath, &QAction::triggered, this, &MainWindow::createPath);
-    connect(m_ui->actionCreateScript, &QAction::triggered, this, &MainWindow::createScript);
-    connect(m_ui->actionCreateFont, &QAction::triggered, this, &MainWindow::createFont);
+    connect(m_ui->actionCreateSprite, &QAction::triggered, this, &MainWindow::createFor<Sprite>);
+    connect(m_ui->actionCreateSound, &QAction::triggered, this, &MainWindow::createFor<Sound>);
+    connect(m_ui->actionCreateBackground, &QAction::triggered, this, &MainWindow::createFor<Background>);
+    connect(m_ui->actionCreatePath, &QAction::triggered, this, &MainWindow::createFor<Path>);
+    connect(m_ui->actionCreateScript, &QAction::triggered, this, &MainWindow::createFor<Script>);
+    connect(m_ui->actionCreateFont, &QAction::triggered, this, &MainWindow::createFor<Font>);
+    connect(m_ui->actionCreateTimeLine, &QAction::triggered, this, &MainWindow::createFor<TimeLine>);
+    connect(m_ui->actionCreateObject, &QAction::triggered, this, &MainWindow::createFor<Object>);
+    connect(m_ui->actionCreateRoom, &QAction::triggered, this, &MainWindow::createFor<Room>);
     connect(m_ui->actionGameInformation, &QAction::triggered, this, &MainWindow::showGameInformation);
     connect(m_ui->actionGlobalGameSettings, &QAction::triggered, this, &MainWindow::showGlobalGameSettings);
     connect(m_ui->actionExtensionPackages, &QAction::triggered, this, &MainWindow::showExtensionPackages);
@@ -180,287 +200,25 @@ void MainWindow::contextMenuRequested(const QPoint &pos)
 
 void MainWindow::doubleClicked(const QModelIndex &index)
 {
-    switch (m_projectTreeModel->nodeType(index))
+    if (m_projectTreeModel->nodeType(index) == ProjectTreeModel::NodeType::Root)
     {
-    case ProjectTreeModel::NodeType::Root:
         if (index == m_projectTreeModel->gameInformationRoot())
             showGameInformation();
         else if (index == m_projectTreeModel->globalGameSettingsRoot())
             showGlobalGameSettings();
         else if (index == m_projectTreeModel->extensionPackagesRoot())
             showExtensionPackages();
-        break;
-    case ProjectTreeModel::NodeType::Sprite:
-    {
-        auto sprite = m_projectTreeModel->getSprite(index);
-        if (!sprite)
-            break;
-
-        if (const auto iter = m_spritePropertiesWindows.find(sprite); iter != std::cend(m_spritePropertiesWindows))
-        {
-            m_ui->mdiArea->setActiveSubWindow(iter->second);
-        }
-        else
-        {
-            auto dialog = new SpritePropertiesDialog{*sprite, *m_projectTreeModel};
-            auto subwindow = m_ui->mdiArea->addSubWindow(dialog);
-            auto action = m_ui->menuWindow->addAction(dialog->windowTitle());
-            action->setCheckable(true);
-            connect(action, &QAction::triggered,
-                    m_ui->mdiArea, [mdiArea=m_ui->mdiArea,subwindow,action](){
-                mdiArea->setActiveSubWindow(subwindow);
-                action->setChecked(subwindow->windowState().testFlag(Qt::WindowActive));
-            });
-            connect(subwindow, &QMdiSubWindow::windowStateChanged,
-                    action, [action](Qt::WindowStates oldState, Qt::WindowStates newState){
-                action->setChecked(newState.testFlag(Qt::WindowActive));
-            });
-            connect(dialog, &QWidget::windowTitleChanged, action, &QAction::setText);
-            connect(dialog, &QDialog::finished,
-                    this, [&spritePropertiesDialogs=m_spritePropertiesWindows,subwindow](){
-                        for (auto iter = std::begin(spritePropertiesDialogs); iter != std::end(spritePropertiesDialogs); )
-                        {
-                            if (iter->second == subwindow)
-                                iter = spritePropertiesDialogs.erase(iter);
-                            else
-                                iter++;
-                        }
-                    });
-            connect(dialog, &QDialog::finished,
-                    subwindow, &QObject::deleteLater);
-            connect(dialog, &QDialog::finished,
-                    action, &QObject::deleteLater);
-            m_spritePropertiesWindows[sprite] = subwindow;
-            dialog->show();
-        }
-        break;
-    }
-    case ProjectTreeModel::NodeType::Sound:
-    {
-        auto sound = m_projectTreeModel->getSound(index);
-        if (!sound)
-            break;
-
-        if (const auto iter = m_soundPropertiesWindows.find(sound); iter != std::cend(m_soundPropertiesWindows))
-        {
-            m_ui->mdiArea->setActiveSubWindow(iter->second);
-        }
-        else
-        {
-            auto dialog = new SoundPropertiesDialog{*sound, *m_projectTreeModel};
-            auto subwindow = m_ui->mdiArea->addSubWindow(dialog);
-            auto action = m_ui->menuWindow->addAction(dialog->windowTitle());
-            action->setCheckable(true);
-            connect(action, &QAction::triggered,
-                    m_ui->mdiArea, [mdiArea=m_ui->mdiArea,subwindow,action](){
-                        mdiArea->setActiveSubWindow(subwindow);
-                        action->setChecked(subwindow->windowState().testFlag(Qt::WindowActive));
-                    });
-            connect(subwindow, &QMdiSubWindow::windowStateChanged,
-                    action, [action](Qt::WindowStates oldState, Qt::WindowStates newState){
-                        action->setChecked(newState.testFlag(Qt::WindowActive));
-                    });
-            connect(dialog, &QWidget::windowTitleChanged, action, &QAction::setText);
-            connect(dialog, &QDialog::finished,
-                    this, [&soundPropertiesDialogs=m_soundPropertiesWindows,subwindow](){
-                        for (auto iter = std::begin(soundPropertiesDialogs); iter != std::end(soundPropertiesDialogs); )
-                        {
-                            if (iter->second == subwindow)
-                                iter = soundPropertiesDialogs.erase(iter);
-                            else
-                                iter++;
-                        }
-                    });
-            connect(dialog, &QDialog::finished,
-                    subwindow, &QObject::deleteLater);
-            connect(dialog, &QDialog::finished,
-                    action, &QObject::deleteLater);
-            m_soundPropertiesWindows[sound] = subwindow;
-            dialog->show();
-        }
-        break;
-    }
-    case ProjectTreeModel::NodeType::Background:
-    {
-        auto background = m_projectTreeModel->getBackground(index);
-        if (!background)
-            break;
-
-        if (const auto iter = m_backgroundPropertiesWindows.find(background); iter != std::cend(m_backgroundPropertiesWindows))
-        {
-            m_ui->mdiArea->setActiveSubWindow(iter->second);
-        }
-        else
-        {
-            auto dialog = new BackgroundPropertiesDialog{*background, *m_projectTreeModel};
-            auto subwindow = m_ui->mdiArea->addSubWindow(dialog);
-            auto action = m_ui->menuWindow->addAction(dialog->windowTitle());
-            action->setCheckable(true);
-            connect(action, &QAction::triggered,
-                    m_ui->mdiArea, [mdiArea=m_ui->mdiArea,subwindow,action](){
-                        mdiArea->setActiveSubWindow(subwindow);
-                        action->setChecked(subwindow->windowState().testFlag(Qt::WindowActive));
-                    });
-            connect(subwindow, &QMdiSubWindow::windowStateChanged,
-                    action, [action](Qt::WindowStates oldState, Qt::WindowStates newState){
-                        action->setChecked(newState.testFlag(Qt::WindowActive));
-                    });
-            connect(dialog, &QWidget::windowTitleChanged, action, &QAction::setText);
-            connect(dialog, &QDialog::finished,
-                    this, [&backgroundPropertiesDialogs=m_backgroundPropertiesWindows,subwindow](){
-                        for (auto iter = std::begin(backgroundPropertiesDialogs); iter != std::end(backgroundPropertiesDialogs); )
-                        {
-                            if (iter->second == subwindow)
-                                iter = backgroundPropertiesDialogs.erase(iter);
-                            else
-                                iter++;
-                        }
-                    });
-            connect(dialog, &QDialog::finished,
-                    subwindow, &QObject::deleteLater);
-            connect(dialog, &QDialog::finished,
-                    action, &QObject::deleteLater);
-            m_backgroundPropertiesWindows[background] = subwindow;
-            dialog->show();
-        }
-        break;
-    }
-    case ProjectTreeModel::NodeType::Path:
-    {
-        auto path = m_projectTreeModel->getPath(index);
-        if (!path)
-            break;
-
-        if (const auto iter = m_pathPropertiesWindows.find(path); iter != std::cend(m_pathPropertiesWindows))
-        {
-            m_ui->mdiArea->setActiveSubWindow(iter->second);
-        }
-        else
-        {
-            auto dialog = new PathPropertiesDialog{*path, *m_projectTreeModel};
-            auto subwindow = m_ui->mdiArea->addSubWindow(dialog);
-            auto action = m_ui->menuWindow->addAction(dialog->windowTitle());
-            action->setCheckable(true);
-            connect(action, &QAction::triggered,
-                    m_ui->mdiArea, [mdiArea=m_ui->mdiArea,subwindow,action](){
-                        mdiArea->setActiveSubWindow(subwindow);
-                        action->setChecked(subwindow->windowState().testFlag(Qt::WindowActive));
-                    });
-            connect(subwindow, &QMdiSubWindow::windowStateChanged,
-                    action, [action](Qt::WindowStates oldState, Qt::WindowStates newState){
-                        action->setChecked(newState.testFlag(Qt::WindowActive));
-                    });
-            connect(dialog, &QWidget::windowTitleChanged, action, &QAction::setText);
-            connect(dialog, &QDialog::finished,
-                    this, [&pathPropertiesDialogs=m_pathPropertiesWindows,subwindow](){
-                        for (auto iter = std::begin(pathPropertiesDialogs); iter != std::end(pathPropertiesDialogs); )
-                        {
-                            if (iter->second == subwindow)
-                                iter = pathPropertiesDialogs.erase(iter);
-                            else
-                                iter++;
-                        }
-                    });
-            connect(dialog, &QDialog::finished,
-                    subwindow, &QObject::deleteLater);
-            connect(dialog, &QDialog::finished,
-                    action, &QObject::deleteLater);
-            m_pathPropertiesWindows[path] = subwindow;
-            dialog->show();
-        }
-        break;
-    }
-    case ProjectTreeModel::NodeType::Script:
-    {
-        auto script = m_projectTreeModel->getScript(index);
-        if (!script)
-            break;
-
-        if (const auto iter = m_scriptPropertiesWindows.find(script); iter != std::cend(m_scriptPropertiesWindows))
-        {
-            m_ui->mdiArea->setActiveSubWindow(iter->second);
-        }
-        else
-        {
-            auto dialog = new ScriptPropertiesDialog{*script, *m_projectTreeModel};
-            auto subwindow = m_ui->mdiArea->addSubWindow(dialog);
-            auto action = m_ui->menuWindow->addAction(dialog->windowTitle());
-            action->setCheckable(true);
-            connect(action, &QAction::triggered,
-                    m_ui->mdiArea, [mdiArea=m_ui->mdiArea,subwindow,action](){
-                        mdiArea->setActiveSubWindow(subwindow);
-                        action->setChecked(subwindow->windowState().testFlag(Qt::WindowActive));
-                    });
-            connect(subwindow, &QMdiSubWindow::windowStateChanged,
-                    action, [action](Qt::WindowStates oldState, Qt::WindowStates newState){
-                        action->setChecked(newState.testFlag(Qt::WindowActive));
-                    });
-            connect(dialog, &QWidget::windowTitleChanged, action, &QAction::setText);
-            connect(dialog, &QDialog::finished,
-                    this, [&scriptPropertiesDialogs=m_scriptPropertiesWindows,subwindow](){
-                        for (auto iter = std::begin(scriptPropertiesDialogs); iter != std::end(scriptPropertiesDialogs); )
-                        {
-                            if (iter->second == subwindow)
-                                iter = scriptPropertiesDialogs.erase(iter);
-                            else
-                                iter++;
-                        }
-                    });
-            connect(dialog, &QDialog::finished,
-                    subwindow, &QObject::deleteLater);
-            connect(dialog, &QDialog::finished,
-                    action, &QObject::deleteLater);
-            m_scriptPropertiesWindows[script] = subwindow;
-            dialog->show();
-        }
-        break;
-    }
-    case ProjectTreeModel::NodeType::Font:
-    {
-        auto font = m_projectTreeModel->getFont(index);
-        if (!font)
-            break;
-
-        if (const auto iter = m_fontPropertiesWindows.find(font); iter != std::cend(m_fontPropertiesWindows))
-        {
-            m_ui->mdiArea->setActiveSubWindow(iter->second);
-        }
-        else
-        {
-            auto dialog = new FontPropertiesDialog{*font, *m_projectTreeModel};
-            auto subwindow = m_ui->mdiArea->addSubWindow(dialog);
-            auto action = m_ui->menuWindow->addAction(dialog->windowTitle());
-            action->setCheckable(true);
-            connect(action, &QAction::triggered,
-                    m_ui->mdiArea, [mdiArea=m_ui->mdiArea,subwindow,action](){
-                        mdiArea->setActiveSubWindow(subwindow);
-                        action->setChecked(subwindow->windowState().testFlag(Qt::WindowActive));
-                    });
-            connect(subwindow, &QMdiSubWindow::windowStateChanged,
-                    action, [action](Qt::WindowStates oldState, Qt::WindowStates newState){
-                        action->setChecked(newState.testFlag(Qt::WindowActive));
-                    });
-            connect(dialog, &QWidget::windowTitleChanged, action, &QAction::setText);
-            connect(dialog, &QDialog::finished,
-                    this, [&fontPropertiesDialogs=m_fontPropertiesWindows,subwindow](){
-                        for (auto iter = std::begin(fontPropertiesDialogs); iter != std::end(fontPropertiesDialogs); )
-                        {
-                            if (iter->second == subwindow)
-                                iter = fontPropertiesDialogs.erase(iter);
-                            else
-                                iter++;
-                        }
-                    });
-            connect(dialog, &QDialog::finished,
-                    subwindow, &QObject::deleteLater);
-            connect(dialog, &QDialog::finished,
-                    action, &QObject::deleteLater);
-            m_fontPropertiesWindows[font] = subwindow;
-            dialog->show();
-        }
-        break;
-    }
+        return;
     }
+    if (doubleClickedFor<Sprite>(index)) return;
+    if (doubleClickedFor<Sound>(index)) return;
+    if (doubleClickedFor<Background>(index)) return;
+    if (doubleClickedFor<Path>(index)) return;
+    if (doubleClickedFor<Script>(index)) return;
+    if (doubleClickedFor<Font>(index)) return;
+    if (doubleClickedFor<TimeLine>(index)) return;
+    if (doubleClickedFor<Object>(index)) return;
+    if (doubleClickedFor<Room>(index)) return;
 }
 
 void MainWindow::selectionChanged(const QModelIndex &index)
@@ -468,30 +226,30 @@ void MainWindow::selectionChanged(const QModelIndex &index)
     switch (const auto nodeType = m_projectTreeModel->nodeType(index))
     {
     case ProjectTreeModel::NodeType::Root:
-        if (index == m_projectTreeModel->spritesRoot() ||
-            index == m_projectTreeModel->soundsRoot() ||
-            index == m_projectTreeModel->backgroundsRoot() ||
-            index == m_projectTreeModel->pathsRoot() ||
-            index == m_projectTreeModel->scriptsRoot() ||
-            index == m_projectTreeModel->fontsRoot())
+        if (index == m_projectTreeModel->rootFor<Sprite>() ||
+            index == m_projectTreeModel->rootFor<Sound>() ||
+            index == m_projectTreeModel->rootFor<Background>() ||
+            index == m_projectTreeModel->rootFor<Path>() ||
+            index == m_projectTreeModel->rootFor<Script>() ||
+            index == m_projectTreeModel->rootFor<Font>() ||
+            index == m_projectTreeModel->rootFor<TimeLine>() ||
+            index == m_projectTreeModel->rootFor<Object>() ||
+            index == m_projectTreeModel->rootFor<Room>())
         {
             m_ui->actionCreate->setEnabled(true);
             m_ui->actionCreateGroup->setText(tr("Cr&eate Group"));
             m_ui->actionCreateGroup->setEnabled(true);
             m_ui->actionSortByName->setEnabled(true);
 
-            if (index == m_projectTreeModel->spritesRoot())
-                m_ui->actionCreate->setText(tr("&Create Sprite"));
-            else if (index == m_projectTreeModel->soundsRoot())
-                m_ui->actionCreate->setText(tr("&Create Sound"));
-            else if (index == m_projectTreeModel->backgroundsRoot())
-                m_ui->actionCreate->setText(tr("&Create Background"));
-            else if (index == m_projectTreeModel->pathsRoot())
-                m_ui->actionCreate->setText(tr("&Create Path"));
-            else if (index == m_projectTreeModel->scriptsRoot())
-                m_ui->actionCreate->setText(tr("&Create Script"));
-            else if (index == m_projectTreeModel->fontsRoot())
-                m_ui->actionCreate->setText(tr("&Create Font"));
+            if (index == m_projectTreeModel->rootFor<Sprite>())          m_ui->actionCreate->setText(tr("&Create Sprite"));
+            else if (index == m_projectTreeModel->rootFor<Sound>())      m_ui->actionCreate->setText(tr("&Create Sound"));
+            else if (index == m_projectTreeModel->rootFor<Background>()) m_ui->actionCreate->setText(tr("&Create Background"));
+            else if (index == m_projectTreeModel->rootFor<Path>())       m_ui->actionCreate->setText(tr("&Create Path"));
+            else if (index == m_projectTreeModel->rootFor<Script>())     m_ui->actionCreate->setText(tr("&Create Script"));
+            else if (index == m_projectTreeModel->rootFor<Font>())       m_ui->actionCreate->setText(tr("&Create Font"));
+            else if (index == m_projectTreeModel->rootFor<TimeLine>())   m_ui->actionCreate->setText(tr("&Create Time Line"));
+            else if (index == m_projectTreeModel->rootFor<Object>())     m_ui->actionCreate->setText(tr("&Create Object"));
+            else if (index == m_projectTreeModel->rootFor<Room>())       m_ui->actionCreate->setText(tr("&Create Room"));
         }
         else
         {
@@ -516,6 +274,9 @@ void MainWindow::selectionChanged(const QModelIndex &index)
     case ProjectTreeModel::NodeType::Path:
     case ProjectTreeModel::NodeType::Script:
     case ProjectTreeModel::NodeType::Font:
+    case ProjectTreeModel::NodeType::TimeLine:
+    case ProjectTreeModel::NodeType::Object:
+    case ProjectTreeModel::NodeType::Room:
         m_ui->actionCreate->setEnabled(true);
         switch (nodeType)
         {
@@ -525,6 +286,9 @@ void MainWindow::selectionChanged(const QModelIndex &index)
         case ProjectTreeModel::NodeType::Path:       m_ui->actionCreate->setText(tr("&Insert Path")); break;
         case ProjectTreeModel::NodeType::Script:     m_ui->actionCreate->setText(tr("&Insert Script")); break;
         case ProjectTreeModel::NodeType::Font:       m_ui->actionCreate->setText(tr("&Insert Font")); break;
+        case ProjectTreeModel::NodeType::TimeLine:   m_ui->actionCreate->setText(tr("&Insert Time Line")); break;
+        case ProjectTreeModel::NodeType::Object:     m_ui->actionCreate->setText(tr("&Insert Object")); break;
+        case ProjectTreeModel::NodeType::Room:       m_ui->actionCreate->setText(tr("&Insert Room")); break;
         default:
             __builtin_unreachable();
         }
@@ -737,18 +501,15 @@ void MainWindow::create()
     if (!index.isValid())
         return;
 
-    if (index == m_projectTreeModel->spritesRoot())
-        createSprite();
-    else if (index == m_projectTreeModel->soundsRoot())
-        createSound();
-    else if (index == m_projectTreeModel->backgroundsRoot())
-        createBackground();
-    else if (index == m_projectTreeModel->pathsRoot())
-        createPath();
-    else if (index == m_projectTreeModel->scriptsRoot())
-        createScript();
-    else if (index == m_projectTreeModel->fontsRoot())
-        createFont();
+    if (index == m_projectTreeModel->rootFor<Sprite>())          createFor<Sprite>();
+    else if (index == m_projectTreeModel->rootFor<Sound>())      createFor<Sound>();
+    else if (index == m_projectTreeModel->rootFor<Background>()) createFor<Background>();
+    else if (index == m_projectTreeModel->rootFor<Path>())       createFor<Path>();
+    else if (index == m_projectTreeModel->rootFor<Script>())     createFor<Script>();
+    else if (index == m_projectTreeModel->rootFor<Font>())       createFor<Font>();
+    else if (index == m_projectTreeModel->rootFor<TimeLine>())   createFor<TimeLine>();
+    else if (index == m_projectTreeModel->rootFor<Object>())     createFor<Object>();
+    else if (index == m_projectTreeModel->rootFor<Room>())       createFor<Room>();
     else
     {
         switch (m_projectTreeModel->nodeType(index))
@@ -759,6 +520,9 @@ void MainWindow::create()
         case ProjectTreeModel::NodeType::Path:
         case ProjectTreeModel::NodeType::Script:
         case ProjectTreeModel::NodeType::Font:
+        case ProjectTreeModel::NodeType::TimeLine:
+        case ProjectTreeModel::NodeType::Object:
+        case ProjectTreeModel::NodeType::Room:
             if (!m_projectTreeModel->insertRows(index.row(), 1, index.parent()))
                 QMessageBox::warning(this, tr("Inserting failed!"), tr("Inserting failed!"));
             break;
@@ -850,41 +614,22 @@ void MainWindow::showObjectInformation()
     }
 }
 
-void MainWindow::createSprite()
+template<typename T>
+void MainWindow::createFor()
 {
-    if (!m_projectTreeModel->insertRows(m_project.sprites.size(), 1, m_projectTreeModel->spritesRoot()))
-        QMessageBox::warning(this, tr("Creating Sprite failed!"), tr("Creating Sprite failed!"));
+    if (!m_projectTreeModel->insertRows(m_project.containerFor<T>().size(), 1, m_projectTreeModel->rootFor<T>()))
+        QMessageBox::warning(this, tr("Creating failed!"), tr("Creating failed!"));
 }
 
-void MainWindow::createSound()
-{
-    if (!m_projectTreeModel->insertRows(m_project.sounds.size(), 1, m_projectTreeModel->soundsRoot()))
-        QMessageBox::warning(this, tr("Creating Sound failed!"), tr("Creating Sound failed!"));
-}
-
-void MainWindow::createBackground()
-{
-    if (!m_projectTreeModel->insertRows(m_project.backgrounds.size(), 1, m_projectTreeModel->backgroundsRoot()))
-        QMessageBox::warning(this, tr("Creating Background failed!"), tr("Creating Background failed!"));
-}
-
-void MainWindow::createPath()
-{
-    if (!m_projectTreeModel->insertRows(m_project.paths.size(), 1, m_projectTreeModel->pathsRoot()))
-        QMessageBox::warning(this, tr("Creating Path failed!"), tr("Creating Path failed!"));
-}
-
-void MainWindow::createScript()
-{
-    if (!m_projectTreeModel->insertRows(m_project.scripts.size(), 1, m_projectTreeModel->scriptsRoot()))
-        QMessageBox::warning(this, tr("Creating Script failed!"), tr("Creating Script failed!"));
-}
-
-void MainWindow::createFont()
-{
-    if (!m_projectTreeModel->insertRows(m_project.fonts.size(), 1, m_projectTreeModel->fontsRoot()))
-        QMessageBox::warning(this, tr("Creating Font failed!"), tr("Creating Font failed!"));
-}
+template void MainWindow::createFor<Sprite>();
+template void MainWindow::createFor<Sound>();
+template void MainWindow::createFor<Background>();
+template void MainWindow::createFor<Path>();
+template void MainWindow::createFor<Script>();
+template void MainWindow::createFor<Font>();
+template void MainWindow::createFor<TimeLine>();
+template void MainWindow::createFor<Object>();
+template void MainWindow::createFor<Room>();
 
 void MainWindow::showGameInformation()
 {
@@ -917,112 +662,28 @@ void MainWindow::rowsInserted(const QModelIndex &parent, int first, int last)
 
 void MainWindow::rowsAboutToBeRemoved(const QModelIndex &parent, int first, int last)
 {
-    if (parent == m_projectTreeModel->spritesRoot())
-    {
-        for (int row = first; row <= last; row++)
-        {
-            if (const auto sprite = m_projectTreeModel->getSprite(m_projectTreeModel->index(row, 0, parent)))
-            {
-                if (const auto iter = m_spritePropertiesWindows.find(sprite); iter != std::end(m_spritePropertiesWindows))
-                {
-                    delete iter->second;
-                    m_spritePropertiesWindows.erase(iter);
-                }
-            }
-        }
-    }
-    else if (parent == m_projectTreeModel->soundsRoot())
-    {
-        for (int row = first; row <= last; row++)
-        {
-            if (const auto sound = m_projectTreeModel->getSound(m_projectTreeModel->index(row, 0, parent)))
-            {
-                if (const auto iter = m_soundPropertiesWindows.find(sound); iter != std::end(m_soundPropertiesWindows))
-                {
-                    delete iter->second;
-                    m_soundPropertiesWindows.erase(iter);
-                }
-            }
-        }
-    }
-    else if (parent == m_projectTreeModel->backgroundsRoot())
-    {
-        for (int row = first; row <= last; row++)
-        {
-            if (const auto background = m_projectTreeModel->getBackground(m_projectTreeModel->index(row, 0, parent)))
-            {
-                if (const auto iter = m_backgroundPropertiesWindows.find(background); iter != std::end(m_backgroundPropertiesWindows))
-                {
-                    delete iter->second;
-                    m_backgroundPropertiesWindows.erase(iter);
-                }
-            }
-        }
-    }
-    else if (parent == m_projectTreeModel->pathsRoot())
-    {
-        for (int row = first; row <= last; row++)
-        {
-            if (const auto path = m_projectTreeModel->getPath(m_projectTreeModel->index(row, 0, parent)))
-            {
-                if (const auto iter = m_pathPropertiesWindows.find(path); iter != std::end(m_pathPropertiesWindows))
-                {
-                    delete iter->second;
-                    m_pathPropertiesWindows.erase(iter);
-                }
-            }
-        }
-    }
-    else if (parent == m_projectTreeModel->scriptsRoot())
-    {
-        for (int row = first; row <= last; row++)
-        {
-            if (const auto script = m_projectTreeModel->getScript(m_projectTreeModel->index(row, 0, parent)))
-            {
-                if (const auto iter = m_scriptPropertiesWindows.find(script); iter != std::end(m_scriptPropertiesWindows))
-                {
-                    delete iter->second;
-                    m_scriptPropertiesWindows.erase(iter);
-                }
-            }
-        }
-    }
-    else if (parent == m_projectTreeModel->fontsRoot())
-    {
-        for (int row = first; row <= last; row++)
-        {
-            if (const auto font = m_projectTreeModel->getFont(m_projectTreeModel->index(row, 0, parent)))
-            {
-                if (const auto iter = m_fontPropertiesWindows.find(font); iter != std::end(m_fontPropertiesWindows))
-                {
-                    delete iter->second;
-                    m_fontPropertiesWindows.erase(iter);
-                }
-            }
-        }
-    }
+    if (rowsAboutToBeRemovedFor<Sprite>(parent, first, last)) return;
+    if (rowsAboutToBeRemovedFor<Sound>(parent, first, last)) return;
+    if (rowsAboutToBeRemovedFor<Background>(parent, first, last)) return;
+    if (rowsAboutToBeRemovedFor<Path>(parent, first, last)) return;
+    if (rowsAboutToBeRemovedFor<Script>(parent, first, last)) return;
+    if (rowsAboutToBeRemovedFor<Font>(parent, first, last)) return;
+    if (rowsAboutToBeRemovedFor<TimeLine>(parent, first, last)) return;
+    if (rowsAboutToBeRemovedFor<Object>(parent, first, last)) return;
+    if (rowsAboutToBeRemovedFor<Room>(parent, first, last)) return;
 }
 
 void MainWindow::modelAboutToBeReset()
 {
-    for (const auto &pair : m_spritePropertiesWindows)
-        delete pair.second;
-    m_spritePropertiesWindows.clear();
-    for (const auto &pair : m_soundPropertiesWindows)
-        delete pair.second;
-    m_soundPropertiesWindows.clear();
-    for (const auto &pair : m_backgroundPropertiesWindows)
-        delete pair.second;
-    m_backgroundPropertiesWindows.clear();
-    for (const auto &pair : m_pathPropertiesWindows)
-        delete pair.second;
-    m_pathPropertiesWindows.clear();
-    for (const auto &pair : m_scriptPropertiesWindows)
-        delete pair.second;
-    m_scriptPropertiesWindows.clear();
-    for (const auto &pair : m_fontPropertiesWindows)
-        delete pair.second;
-    m_fontPropertiesWindows.clear();
+    modelAboutToBeResetFor<Sprite>();
+    modelAboutToBeResetFor<Sound>();
+    modelAboutToBeResetFor<Background>();
+    modelAboutToBeResetFor<Path>();
+    modelAboutToBeResetFor<Script>();
+    modelAboutToBeResetFor<Font>();
+    modelAboutToBeResetFor<TimeLine>();
+    modelAboutToBeResetFor<Object>();
+    modelAboutToBeResetFor<Room>();
 }
 
 void MainWindow::updateTitle()
@@ -1031,3 +692,140 @@ void MainWindow::updateTitle()
                        .arg(m_filePath.isEmpty() ? "<new-game>" : QFileInfo{m_filePath}.fileName())
                        .arg(m_unsavedChanges ? tr("*") : QString{}));
 }
+
+template<typename T>
+bool MainWindow::doubleClickedFor(const QModelIndex &index)
+{
+    if (m_projectTreeModel->nodeType(index) != ProjectTreeModel::nodeTypeFor<T>())
+        return false;
+
+    auto entry = m_projectTreeModel->get<T>(index);
+    if (!entry)
+        return true;
+
+    auto &propertyWindows = propertyWindowsFor<T>();
+    if (const auto iter = propertyWindows.find(entry); iter != std::cend(propertyWindows))
+    {
+        m_ui->mdiArea->setActiveSubWindow(iter->second);
+    }
+    else
+    {
+        auto dialog = new PropertiesDialogFor<T>{*entry, *m_projectTreeModel};
+        auto subwindow = m_ui->mdiArea->addSubWindow(dialog);
+        auto action = m_ui->menuWindow->addAction(dialog->windowTitle());
+        action->setCheckable(true);
+        connect(action, &QAction::triggered,
+                m_ui->mdiArea, [mdiArea=m_ui->mdiArea,subwindow,action](){
+                    mdiArea->setActiveSubWindow(subwindow);
+                    action->setChecked(subwindow->windowState().testFlag(Qt::WindowActive));
+                });
+        connect(subwindow, &QMdiSubWindow::windowStateChanged,
+                action, [action](Qt::WindowStates oldState, Qt::WindowStates newState){
+                    action->setChecked(newState.testFlag(Qt::WindowActive));
+                });
+        connect(dialog, &QWidget::windowTitleChanged, action, &QAction::setText);
+        connect(dialog, &QDialog::finished,
+                this, [&propertyWindows,subwindow](){
+                    for (auto iter = std::begin(propertyWindows); iter != std::end(propertyWindows); )
+                    {
+                        if (iter->second == subwindow)
+                            iter = propertyWindows.erase(iter);
+                        else
+                            iter++;
+                    }
+                });
+        connect(dialog, &QDialog::finished,
+                subwindow, &QObject::deleteLater);
+        connect(dialog, &QDialog::finished,
+                action, &QObject::deleteLater);
+        propertyWindows[entry] = subwindow;
+        dialog->show();
+    }
+
+    return true;
+}
+
+template<typename T>
+bool MainWindow::rowsAboutToBeRemovedFor(const QModelIndex &parent, int first, int last)
+{
+    if (parent != m_projectTreeModel->rootFor<T>())
+        return false;
+
+    for (int row = first; row <= last; row++)
+    {
+        if (const auto entry = m_projectTreeModel->get<T>(m_projectTreeModel->index(row, 0, parent)))
+        {
+            auto &propertyWindows = propertyWindowsFor<T>();
+            if (const auto iter = propertyWindows.find(entry); iter != std::end(propertyWindows))
+            {
+                delete iter->second;
+                propertyWindows.erase(iter);
+            }
+        }
+    }
+
+    return true;
+}
+
+template<typename T>
+void MainWindow::modelAboutToBeResetFor()
+{
+    auto &propertyWindows = propertyWindowsFor<T>();
+    for (const auto &pair : propertyWindows)
+        delete pair.second;
+    propertyWindows.clear();
+}
+
+template<>
+std::map<Sprite*, QMdiSubWindow*> &MainWindow::propertyWindowsFor<Sprite>()
+{
+    return m_spritePropertiesWindows;
+}
+
+template<>
+std::map<Sound*, QMdiSubWindow*> &MainWindow::propertyWindowsFor<Sound>()
+{
+    return m_soundPropertiesWindows;
+}
+
+template<>
+std::map<Background*, QMdiSubWindow*> &MainWindow::propertyWindowsFor<Background>()
+{
+    return m_backgroundPropertiesWindows;
+}
+
+template<>
+std::map<Path*, QMdiSubWindow*> &MainWindow::propertyWindowsFor<Path>()
+{
+    return m_pathPropertiesWindows;
+}
+
+template<>
+std::map<Script*, QMdiSubWindow*> &MainWindow::propertyWindowsFor<Script>()
+{
+    return m_scriptPropertiesWindows;
+}
+
+template<>
+std::map<Font*, QMdiSubWindow*> &MainWindow::propertyWindowsFor<Font>()
+{
+    return m_fontPropertiesWindows;
+}
+
+template<>
+std::map<TimeLine*, QMdiSubWindow*> &MainWindow::propertyWindowsFor<TimeLine>()
+{
+    return m_timeLinePropertiesWindows;
+}
+
+template<>
+std::map<Object*, QMdiSubWindow*> &MainWindow::propertyWindowsFor<Object>()
+{
+    return m_objectPropertiesWindows;
+}
+
+template<>
+std::map<Room*, QMdiSubWindow*> &MainWindow::propertyWindowsFor<Room>()
+{
+    return m_roomPropertiesWindows;
+}
diff --git a/mainwindow.h b/mainwindow.h
index 67f3228..ad0ead9 100644
--- a/mainwindow.h
+++ b/mainwindow.h
@@ -46,12 +46,19 @@ private slots:
     void showProperties();
     void findResource();
     void showObjectInformation();
-    void createSprite();
-    void createSound();
-    void createBackground();
-    void createPath();
-    void createScript();
-    void createFont();
+private:
+    template<typename T>
+    void createFor();
+private slots:
+//    void createSprite();
+//    void createSound();
+//    void createBackground();
+//    void createPath();
+//    void createScript();
+//    void createFont();
+//    void createTimeLine();
+//    void createObject();
+//    void createRoom();
     void showGameInformation();
     void showGlobalGameSettings();
     void showExtensionPackages();
@@ -64,6 +71,18 @@ private slots:
 private:
     void updateTitle();
 
+    template<typename T>
+    std::map<T*, QMdiSubWindow*> &propertyWindowsFor();
+
+    template<typename T>
+    bool doubleClickedFor(const QModelIndex &index);
+
+    template<typename T>
+    bool rowsAboutToBeRemovedFor(const QModelIndex &parent, int first, int last);
+
+    template<typename T>
+    void modelAboutToBeResetFor();
+
     const std::unique_ptr<Ui::MainWindow> m_ui;
 
     ProjectContainer m_project;
@@ -79,6 +98,9 @@ private:
     std::map<Path*, QMdiSubWindow*> m_pathPropertiesWindows;
     std::map<Script*, QMdiSubWindow*> m_scriptPropertiesWindows;
     std::map<Font*, QMdiSubWindow*> m_fontPropertiesWindows;
+    std::map<TimeLine*, QMdiSubWindow*> m_timeLinePropertiesWindows;
+    std::map<Object*, QMdiSubWindow*> m_objectPropertiesWindows;
+    std::map<Room*, QMdiSubWindow*> m_roomPropertiesWindows;
 
     QMdiSubWindow *m_objectInformationWindow{};
 };
diff --git a/projectcontainer.cpp b/projectcontainer.cpp
index d7141d3..f0db2ae 100644
--- a/projectcontainer.cpp
+++ b/projectcontainer.cpp
@@ -1,14 +1,82 @@
 #include "projectcontainer.h"
 
+template<> std::list<Sprite> &ProjectContainer::containerFor() { return sprites; }
+template<> const std::list<Sprite> &ProjectContainer::containerFor() const { return sprites; }
+template<> std::list<Sound> &ProjectContainer::containerFor() { return sounds; }
+template<> const std::list<Sound> &ProjectContainer::containerFor() const { return sounds; }
+template<> std::list<Background> &ProjectContainer::containerFor() { return backgrounds; }
+template<> const std::list<Background> &ProjectContainer::containerFor() const { return backgrounds; }
+template<> std::list<Path> &ProjectContainer::containerFor() { return paths; }
+template<> const std::list<Path> &ProjectContainer::containerFor() const { return paths; }
+template<> std::list<Script> &ProjectContainer::containerFor() { return scripts; }
+template<> const std::list<Script> &ProjectContainer::containerFor() const { return scripts; }
+template<> std::list<Font> &ProjectContainer::containerFor() { return fonts; }
+template<> const std::list<Font> &ProjectContainer::containerFor() const { return fonts; }
+template<> std::list<TimeLine> &ProjectContainer::containerFor() { return timeLines; }
+template<> const std::list<TimeLine> &ProjectContainer::containerFor() const { return timeLines; }
+template<> std::list<Object> &ProjectContainer::containerFor() { return objects; }
+template<> const std::list<Object> &ProjectContainer::containerFor() const { return objects; }
+template<> std::list<Room> &ProjectContainer::containerFor() { return rooms; }
+template<> const std::list<Room> &ProjectContainer::containerFor() const { return rooms; }
+
+template<typename T>
+QDataStream &operator<<(QDataStream &ds, const std::list<T> &list)
+{
+    {
+        int entries = list.size();
+        ds << entries;
+    }
+    for (const auto &entry : list)
+        ds << entry;
+    return ds;
+}
+
+template<typename T>
+QDataStream &operator>>(QDataStream &ds, std::list<T> &list)
+{
+    int entries;
+    ds >> entries;
+
+    for (int i = 0; i < entries; i++)
+    {
+        T entry;
+        ds >> entry;
+        list.emplace_back(std::move(entry));
+    }
+    return ds;
+}
+
+template<typename T>
+QDataStream &operator<<(QDataStream &ds, const std::vector<T> &list)
+{
+    {
+        int entries = list.size();
+        ds << entries;
+    }
+    for (const auto &entry : list)
+        ds << entry;
+    return ds;
+}
+
+template<typename T>
+QDataStream &operator>>(QDataStream &ds, std::vector<T> &list)
+{
+    int entries;
+    ds >> entries;
+
+    for (int i = 0; i < entries; i++)
+    {
+        T entry;
+        ds >> entry;
+        list.emplace_back(std::move(entry));
+    }
+    return ds;
+}
+
 QDataStream &operator<<(QDataStream &ds, const Sprite &sprite)
 {
     ds << sprite.name;
-    {
-        int pixmaps = sprite.pixmaps.size();
-        ds << pixmaps;
-    }
-    for (const auto &pixmap : sprite.pixmaps)
-        ds << pixmap;
+    ds << sprite.pixmaps;
     ds << sprite.origin.x;
     ds << sprite.origin.y;
     ds << sprite.preciseCollisionChecking;
@@ -19,17 +87,7 @@ QDataStream &operator<<(QDataStream &ds, const Sprite &sprite)
 QDataStream &operator>>(QDataStream &ds, Sprite &sprite)
 {
     ds >> sprite.name;
-    {
-        int pixmaps;
-        ds >> pixmaps;
-
-        for (int i = 0; i < pixmaps; i++)
-        {
-            QPixmap pixmap;
-            ds >> pixmap;
-            sprite.pixmaps.emplace_back(std::move(pixmap));
-        }
-    }
+    ds >> sprite.pixmaps;
     ds >> sprite.origin.x;
     ds >> sprite.origin.y;
     ds >> sprite.preciseCollisionChecking;
@@ -125,115 +183,67 @@ QDataStream &operator>>(QDataStream &ds, Font &font)
     return ds;
 }
 
+QDataStream &operator<<(QDataStream &ds, const TimeLine &timeLine)
+{
+    ds << timeLine.name;
+    return ds;
+}
+
+QDataStream &operator>>(QDataStream &ds, TimeLine &timeLine)
+{
+    ds >> timeLine.name;
+    return ds;
+}
+
+QDataStream &operator<<(QDataStream &ds, const Object &object)
+{
+    ds << object.name;
+    return ds;
+}
+
+QDataStream &operator>>(QDataStream &ds, Object &object)
+{
+    ds >> object.name;
+    return ds;
+}
+
+QDataStream &operator<<(QDataStream &ds, const Room &room)
+{
+    ds << room.name;
+    return ds;
+}
+
+QDataStream &operator>>(QDataStream &ds, Room &room)
+{
+    ds >> room.name;
+    return ds;
+}
+
 QDataStream &operator<<(QDataStream &ds, const ProjectContainer &project)
 {
-    {
-        int sprites = project.sprites.size();
-        ds << sprites;
-        for (const auto &sprite : project.sprites)
-            ds << sprite;
-    }
-    {
-        int sounds = project.sounds.size();
-        ds << sounds;
-        for (const auto &sound : project.sounds)
-            ds << sound;
-    }
-    {
-        int backgrounds = project.backgrounds.size();
-        ds << backgrounds;
-        for (const auto &background : project.backgrounds)
-            ds << background;
-    }
-    {
-        int paths = project.paths.size();
-        ds << paths;
-        for (const auto &path : project.paths)
-            ds << path;
-    }
-    {
-        int scripts = project.scripts.size();
-        ds << scripts;
-        for (const auto &script : project.scripts)
-            ds << script;
-    }
-    {
-        int fonts = project.fonts.size();
-        ds << fonts;
-        for (const auto &font : project.fonts)
-            ds << font;
-    }
+    ds << project.sprites;
+    ds << project.sounds;
+    ds << project.backgrounds;
+    ds << project.paths;
+    ds << project.scripts;
+    ds << project.fonts;
+    ds << project.timeLines;
+    ds << project.objects;
+    ds << project.rooms;
     return ds;
 }
 
 QDataStream &operator>>(QDataStream &ds, ProjectContainer &project)
 {
-    {
-        int sprites;
-        ds >> sprites;
-
-        for (int i = 0; i < sprites; i++)
-        {
-            Sprite sprite;
-            ds >> sprite;
-            project.sprites.emplace_back(std::move(sprite));
-        }
-    }
-    {
-        int sounds;
-        ds >> sounds;
-
-        for (int i = 0; i < sounds; i++)
-        {
-            Sound sound;
-            ds >> sound;
-            project.sounds.emplace_back(std::move(sound));
-        }
-    }
-    {
-        int backgrounds;
-        ds >> backgrounds;
-
-        for (int i = 0; i < backgrounds; i++)
-        {
-            Background background;
-            ds >> background;
-            project.backgrounds.emplace_back(std::move(background));
-        }
-    }
-    {
-        int paths;
-        ds >> paths;
-
-        for (int i = 0; i < paths; i++)
-        {
-            Path path;
-            ds >> path;
-            project.paths.emplace_back(std::move(path));
-        }
-    }
-    {
-        int scripts;
-        ds >> scripts;
-
-        for (int i = 0; i < scripts; i++)
-        {
-            Script script;
-            ds >> script;
-            project.scripts.emplace_back(std::move(script));
-        }
-    }
-    {
-        int fonts;
-        ds >> fonts;
-
-        for (int i = 0; i < fonts; i++)
-        {
-            Font font;
-            ds >> font;
-            project.fonts.emplace_back(std::move(font));
-        }
-    }
+    ds >> project.sprites;
+    ds >> project.sounds;
+    ds >> project.backgrounds;
+    ds >> project.paths;
+    ds >> project.scripts;
+    ds >> project.fonts;
+    ds >> project.timeLines;
+    ds >> project.objects;
+    ds >> project.rooms;
     return ds;
 }
 
diff --git a/projectcontainer.h b/projectcontainer.h
index efc90b2..628df50 100644
--- a/projectcontainer.h
+++ b/projectcontainer.h
@@ -24,7 +24,7 @@ struct Sound
 {
     QString name;
     enum class Type { Sound, Music };
-    Type type;
+    Type type{Type::Sound};
     QString path;
     struct {
         bool chorus{};
@@ -67,14 +67,35 @@ struct Font
     } range;
 };
 
+struct TimeLine
+{
+    QString name;
+};
+
+struct Object
+{
+    QString name;
+};
+
+struct Room
+{
+    QString name;
+};
+
 struct ProjectContainer
 {
     std::list<Sprite> sprites;
-    std::list<Sound> sounds;    
+    std::list<Sound> sounds;
     std::list<Background> backgrounds;
     std::list<Path> paths;
     std::list<Script> scripts;
     std::list<Font> fonts;
+    std::list<TimeLine> timeLines;
+    std::list<Object> objects;
+    std::list<Room> rooms;
+
+    template<typename T> std::list<T> &containerFor();
+    template<typename T> const std::list<T> &containerFor() const;
 };
 
 QDataStream &operator<<(QDataStream &ds, const Sprite &sprite);
@@ -89,5 +110,11 @@ QDataStream &operator<<(QDataStream &ds, const Script &script);
 QDataStream &operator>>(QDataStream &ds, Script &script);
 QDataStream &operator<<(QDataStream &ds, const Font &font);
 QDataStream &operator>>(QDataStream &ds, Font &font);
+QDataStream &operator<<(QDataStream &ds, const TimeLine &timeLine);
+QDataStream &operator>>(QDataStream &ds, TimeLine &timeLine);
+QDataStream &operator<<(QDataStream &ds, const Object &object);
+QDataStream &operator>>(QDataStream &ds, Object &object);
+QDataStream &operator<<(QDataStream &ds, const Room &room);
+QDataStream &operator>>(QDataStream &ds, Room &room);
 QDataStream &operator<<(QDataStream &ds, const ProjectContainer &project);
 QDataStream &operator>>(QDataStream &ds, ProjectContainer &project);
diff --git a/projecttreemodel.cpp b/projecttreemodel.cpp
index e06ae82..06ab4ae 100644
--- a/projecttreemodel.cpp
+++ b/projecttreemodel.cpp
@@ -9,6 +9,7 @@
 #include "futurecpp.h"
 #include "projectcontainer.h"
 
+namespace {
 enum {
     RowSprites,
     RowSounds,
@@ -24,6 +25,7 @@ enum {
     RowExtensionPackages,
     NumberOfRows
 };
+}
 
 ProjectTreeModel::ProjectTreeModel(QObject *parent) :
     QAbstractItemModel{parent}
@@ -53,6 +55,9 @@ QModelIndex ProjectTreeModel::index(int row, int column, const QModelIndex &pare
             case RowPaths:       return createIndex(row, column, std::to_underlying(NodeType::Path));
             case RowScripts:     return createIndex(row, column, std::to_underlying(NodeType::Script));
             case RowFonts:       return createIndex(row, column, std::to_underlying(NodeType::Font));
+            case RowTimeLines:   return createIndex(row, column, std::to_underlying(NodeType::TimeLine));
+            case RowObjects:     return createIndex(row, column, std::to_underlying(NodeType::Object));
+            case RowRooms:       return createIndex(row, column, std::to_underlying(NodeType::Room));
             default:
                 qWarning() << "unexpected parent row" << parent.row();
                 return {};
@@ -74,12 +79,15 @@ QModelIndex ProjectTreeModel::parent(const QModelIndex &child) const
     switch (nodeType(child))
     {
     case NodeType::Root:       return {};
-    case NodeType::Sprite:     return spritesRoot();
-    case NodeType::Sound:      return soundsRoot();
-    case NodeType::Background: return backgroundsRoot();
-    case NodeType::Path:       return pathsRoot();
-    case NodeType::Script:     return scriptsRoot();
-    case NodeType::Font:       return fontsRoot();
+    case NodeType::Sprite:     return rootFor<Sprite>();
+    case NodeType::Sound:      return rootFor<Sound>();
+    case NodeType::Background: return rootFor<Background>();
+    case NodeType::Path:       return rootFor<Path>();
+    case NodeType::Script:     return rootFor<Script>();
+    case NodeType::Font:       return rootFor<Font>();
+    case NodeType::TimeLine:   return rootFor<TimeLine>();
+    case NodeType::Object:     return rootFor<Object>();
+    case NodeType::Room:       return rootFor<Room>();
     default:
         qWarning() << "unexpected child type" << child.internalId();
         return {};
@@ -96,15 +104,15 @@ int ProjectTreeModel::rowCount(const QModelIndex &parent) const
     case NodeType::Root:
         switch (parent.row())
         {
-        case RowSprites:     return m_project ? m_project->sprites.size() : 0;
-        case RowSounds:      return m_project ? m_project->sounds.size() : 0;
-        case RowBackgrounds: return m_project ? m_project->backgrounds.size() : 0;
-        case RowPaths:       return m_project ? m_project->paths.size() : 0;
-        case RowScripts:     return m_project ? m_project->scripts.size() : 0;
-        case RowFonts:       return m_project ? m_project->fonts.size() : 0;
-        case RowTimeLines:
-        case RowObjects:
-        case RowRooms:
+        case RowSprites:     return m_project ? m_project->containerFor<Sprite>().size() : 0;
+        case RowSounds:      return m_project ? m_project->containerFor<Sound>().size() : 0;
+        case RowBackgrounds: return m_project ? m_project->containerFor<Background>().size() : 0;
+        case RowPaths:       return m_project ? m_project->containerFor<Path>().size() : 0;
+        case RowScripts:     return m_project ? m_project->containerFor<Script>().size() : 0;
+        case RowFonts:       return m_project ? m_project->containerFor<Font>().size() : 0;
+        case RowTimeLines:   return m_project ? m_project->containerFor<TimeLine>().size() : 0;
+        case RowObjects:     return m_project ? m_project->containerFor<Object>().size() : 0;
+        case RowRooms:       return m_project ? m_project->containerFor<Room>().size() : 0;
         case RowGameInformation:
         case RowGlobalGameSettings:
         case RowExtensionPackages:
@@ -115,12 +123,16 @@ int ProjectTreeModel::rowCount(const QModelIndex &parent) const
         }
 
         return {};
-    case NodeType::Sprite:     return 0;
-    case NodeType::Sound:      return 0;
-    case NodeType::Background: return 0;
-    case NodeType::Path:       return 0;
-    case NodeType::Script:     return 0;
-    case NodeType::Font:       return 0;
+    case NodeType::Sprite:
+    case NodeType::Sound:
+    case NodeType::Background:
+    case NodeType::Path:
+    case NodeType::Script:
+    case NodeType::Font:
+    case NodeType::TimeLine:
+    case NodeType::Object:
+    case NodeType::Room:
+        return 0;
     default:
         qWarning() << "unexpected parent child type" << parent.internalId();
         return -1;
@@ -156,12 +168,16 @@ int ProjectTreeModel::columnCount(const QModelIndex &parent) const
         }
 
         return {};
-    case NodeType::Sprite:     return 1;
-    case NodeType::Sound:      return 1;
-    case NodeType::Background: return 1;
-    case NodeType::Path:       return 1;
-    case NodeType::Script:     return 1;
-    case NodeType::Font:       return 1;
+    case NodeType::Sprite:
+    case NodeType::Sound:
+    case NodeType::Background:
+    case NodeType::Path:
+    case NodeType::Script:
+    case NodeType::Font:
+    case NodeType::TimeLine:
+    case NodeType::Object:
+    case NodeType::Room:
+        return 1;
     default:
         qWarning() << "unexpected parent child type" << parent.internalId();
         return -1;
@@ -224,191 +240,15 @@ QVariant ProjectTreeModel::data(const QModelIndex &index, int role) const
         default:
             return {};
         }
-    case NodeType::Sprite:
-    {
-        if (!m_project)
-        {
-            qWarning() << "unexpected null project";
-            return {};
-        }
-
-        if (index.row() >= m_project->sprites.size())
-        {
-            qWarning() << "sprite index out of bounds" << index.row();
-            return {};
-        }
-
-        auto iter = std::next(std::cbegin(m_project->sprites), index.row());
-
-        switch (role)
-        {
-        case Qt::DisplayRole:
-        case Qt::EditRole:
-            return iter->name;
-        case Qt::DecorationRole:
-            if (iter->pixmaps.empty() || iter->pixmaps.front().isNull())
-            {
-                QPixmap pixmap{16, 16};
-                pixmap.fill(Qt::white);
-                return pixmap;
-            }
-            return iter->pixmaps.front().scaled(16, 16, Qt::IgnoreAspectRatio /*KeepAspectRatio*/);
-
-        default:
-            return {};
-        }
-    }
-    case NodeType::Sound:
-    {
-        if (!m_project)
-        {
-            qWarning() << "unexpected null project";
-            return {};
-        }
-
-        if (index.row() >= m_project->sounds.size())
-        {
-            qWarning() << "sound index out of bounds" << index.row();
-            return {};
-        }
-
-        auto iter = std::next(std::cbegin(m_project->sounds), index.row());
-
-        switch (role)
-        {
-        case Qt::DisplayRole:
-        case Qt::EditRole:
-            return iter->name;
-        case Qt::DecorationRole:
-            switch (iter->type)
-            {
-            case Sound::Type::Sound:
-                return QPixmap{":/qtgameengine/icons/sound-file.png"}.scaled(16, 16);
-            case Sound::Type::Music:
-                return QPixmap{":/qtgameengine/icons/music-file.png"}.scaled(16, 16);
-            default:
-                qWarning() << "unexpected sound type" << std::to_underlying(iter->type);
-                return {};
-            }
-
-        default:
-            return {};
-        }
-    }
-    case NodeType::Background:
-    {
-        if (!m_project)
-        {
-            qWarning() << "unexpected null project";
-            return {};
-        }
-
-        if (index.row() >= m_project->backgrounds.size())
-        {
-            qWarning() << "sprite index out of bounds" << index.row();
-            return {};
-        }
-
-        auto iter = std::next(std::cbegin(m_project->backgrounds), index.row());
-
-        switch (role)
-        {
-        case Qt::DisplayRole:
-        case Qt::EditRole:
-            return iter->name;
-        case Qt::DecorationRole:
-            if (iter->pixmap.isNull())
-            {
-                QPixmap pixmap{16, 16};
-                pixmap.fill(Qt::white);
-                return pixmap;
-            }
-            return iter->pixmap.scaled(16, 16, Qt::KeepAspectRatio);
-        default:
-            return {};
-        }
-    }
-    case NodeType::Path:
-    {
-        if (!m_project)
-        {
-            qWarning() << "unexpected null project";
-            return {};
-        }
-
-        if (index.row() >= m_project->paths.size())
-        {
-            qWarning() << "path index out of bounds" << index.row();
-            return {};
-        }
-
-        auto iter = std::next(std::cbegin(m_project->paths), index.row());
-
-        switch (role)
-        {
-        case Qt::DisplayRole:
-        case Qt::EditRole:
-            return iter->name;
-        case Qt::DecorationRole:
-            return QPixmap{":/qtgameengine/icons/path-file.png"}.scaled(16, 16);
-        default:
-            return {};
-        }
-    }
-    case NodeType::Script:
-    {
-        if (!m_project)
-        {
-            qWarning() << "unexpected null project";
-            return {};
-        }
-
-        if (index.row() >= m_project->scripts.size())
-        {
-            qWarning() << "script index out of bounds" << index.row();
-            return {};
-        }
-
-        auto iter = std::next(std::cbegin(m_project->scripts), index.row());
-
-        switch (role)
-        {
-        case Qt::DisplayRole:
-        case Qt::EditRole:
-            return iter->name;
-        case Qt::DecorationRole:
-            return QPixmap{":/qtgameengine/icons/script-file.png"}.scaled(16, 16);
-        default:
-            return {};
-        }
-    }
-    case NodeType::Font:
-    {
-        if (!m_project)
-        {
-            qWarning() << "unexpected null project";
-            return {};
-        }
-
-        if (index.row() >= m_project->fonts.size())
-        {
-            qWarning() << "font index out of bounds" << index.row();
-            return {};
-        }
-
-        auto iter = std::next(std::cbegin(m_project->fonts), index.row());
-
-        switch (role)
-        {
-        case Qt::DisplayRole:
-        case Qt::EditRole:
-            return iter->name;
-        case Qt::DecorationRole:
-            return QPixmap{":/qtgameengine/icons/font-file.png"}.scaled(16, 16);
-        default:
-            return {};
-        }
-    }
+    case NodeType::Sprite:     return dataFor<Sprite>(index, role);
+    case NodeType::Sound:      return dataFor<Sound>(index, role);
+    case NodeType::Background: return dataFor<Background>(index, role);
+    case NodeType::Path:       return dataFor<Path>(index, role);
+    case NodeType::Script:     return dataFor<Script>(index, role);
+    case NodeType::Font:       return dataFor<Font>(index, role);
+    case NodeType::TimeLine:   return dataFor<TimeLine>(index, role);
+    case NodeType::Object:     return dataFor<Object>(index, role);
+    case NodeType::Room:       return dataFor<Room>(index, role);
     default:
         qWarning() << "unexpected index type" << index.internalId();
         return -1;
@@ -427,6 +267,9 @@ Qt::ItemFlags ProjectTreeModel::flags(const QModelIndex &index) const
     case NodeType::Path:
     case NodeType::Script:
     case NodeType::Font:
+    case NodeType::TimeLine:
+    case NodeType::Object:
+    case NodeType::Room:
         flags |= Qt::ItemIsEditable | Qt::ItemIsDragEnabled;
     }
 
@@ -437,228 +280,15 @@ bool ProjectTreeModel::setData(const QModelIndex &index, const QVariant &value,
 {
     switch (const auto nodeType = this->nodeType(index))
     {
-    case NodeType::Sprite:
-    {
-        if (!m_project)
-        {
-            qWarning() << "unexpected null project";
-            return {};
-        }
-
-        if (index.row() < 0 || index.row() >= m_project->sprites.size())
-        {
-            qWarning() << "unexpected sprite row" << index.row();
-            return false;
-        }
-        auto iter = std::next(std::begin(m_project->sprites), index.row());
-        switch (role)
-        {
-        case Qt::DisplayRole:
-        case Qt::EditRole:
-            if (auto name = value.toString(); name != iter->name)
-            {
-                if (std::any_of(std::cbegin(m_project->sprites), std::cend(m_project->sprites),
-                                [&name](const auto &entry){ return entry.name == name; }))
-                {
-                    qWarning() << "duplicate name" << name;
-                    emit errorOccured(tr("A Sprite with the name \"%0\" is already existing").arg(name));
-                    return false;
-                }
-                iter->name = std::move(name);
-                emit spriteNameChanged(*iter);
-                emit dataChanged(index, index, {Qt::DisplayRole, Qt::EditRole});
-            }
-            return true;
-        default:
-            qWarning() << "unexpected role" << role;
-            return false;
-        }
-    }
-    case NodeType::Sound:
-    {
-        if (!m_project)
-        {
-            qWarning() << "unexpected null project";
-            return {};
-        }
-
-        if (index.row() < 0 || index.row() >= m_project->sounds.size())
-        {
-            qWarning() << "unexpected sound row" << index.row();
-            return false;
-        }
-        auto iter = std::next(std::begin(m_project->sounds), index.row());
-        switch (role)
-        {
-        case Qt::DisplayRole:
-        case Qt::EditRole:
-            if (auto name = value.toString(); name != iter->name)
-            {
-                if (std::any_of(std::cbegin(m_project->sprites), std::cend(m_project->sprites),
-                                [&name](const auto &entry){ return entry.name == name; }))
-                {
-                    qWarning() << "duplicate name" << name;
-                    emit errorOccured(tr("A Sound with the name \"%0\" is already existing").arg(name));
-                    return false;
-                }
-                iter->name = std::move(name);
-                emit soundNameChanged(*iter);
-                emit dataChanged(index, index, {Qt::DisplayRole, Qt::EditRole});
-            }
-            return true;
-        default:
-            qWarning() << "unexpected role" << role;
-            return false;
-        }
-    }
-    case NodeType::Background:
-    {
-        if (!m_project)
-        {
-            qWarning() << "unexpected null project";
-            return {};
-        }
-
-        if (index.row() < 0 || index.row() >= m_project->backgrounds.size())
-        {
-            qWarning() << "unexpected background row" << index.row();
-            return false;
-        }
-        auto iter = std::next(std::begin(m_project->backgrounds), index.row());
-        switch (role)
-        {
-        case Qt::DisplayRole:
-        case Qt::EditRole:
-            if (auto name = value.toString(); name != iter->name)
-            {
-                if (std::any_of(std::cbegin(m_project->sprites), std::cend(m_project->sprites),
-                                [&name](const auto &entry){ return entry.name == name; }))
-                {
-                    qWarning() << "duplicate name" << name;
-                    emit errorOccured(tr("A Background with the name \"%0\" is already existing").arg(name));
-                    return false;
-                }
-                iter->name = std::move(name);
-                emit backgroundNameChanged(*iter);
-                emit dataChanged(index, index, {Qt::DisplayRole, Qt::EditRole});
-            }
-            return true;
-        default:
-            qWarning() << "unexpected role" << role;
-            return false;
-        }
-    }
-    case NodeType::Path:
-    {
-        if (!m_project)
-        {
-            qWarning() << "unexpected null project";
-            return {};
-        }
-
-        if (index.row() < 0 || index.row() >= m_project->paths.size())
-        {
-            qWarning() << "unexpected path row" << index.row();
-            return false;
-        }
-        auto iter = std::next(std::begin(m_project->paths), index.row());
-        switch (role)
-        {
-        case Qt::DisplayRole:
-        case Qt::EditRole:
-            if (auto name = value.toString(); name != iter->name)
-            {
-                if (std::any_of(std::cbegin(m_project->sprites), std::cend(m_project->sprites),
-                                [&name](const auto &entry){ return entry.name == name; }))
-                {
-                    qWarning() << "duplicate name" << name;
-                    emit errorOccured(tr("A Path with the name \"%0\" is already existing").arg(name));
-                    return false;
-                }
-                iter->name = std::move(name);
-                emit pathNameChanged(*iter);
-                emit dataChanged(index, index, {Qt::DisplayRole, Qt::EditRole});
-            }
-            return true;
-        default:
-            qWarning() << "unexpected role" << role;
-            return false;
-        }
-    }
-    case NodeType::Script:
-    {
-        if (!m_project)
-        {
-            qWarning() << "unexpected null project";
-            return {};
-        }
-
-        if (index.row() < 0 || index.row() >= m_project->scripts.size())
-        {
-            qWarning() << "unexpected script row" << index.row();
-            return false;
-        }
-        auto iter = std::next(std::begin(m_project->scripts), index.row());
-        switch (role)
-        {
-        case Qt::DisplayRole:
-        case Qt::EditRole:
-            if (auto name = value.toString(); name != iter->name)
-            {
-                if (std::any_of(std::cbegin(m_project->sprites), std::cend(m_project->sprites),
-                                [&name](const auto &entry){ return entry.name == name; }))
-                {
-                    qWarning() << "duplicate name" << name;
-                    emit errorOccured(tr("A Script with the name \"%0\" is already existing").arg(name));
-                    return false;
-                }
-                iter->name = std::move(name);
-                emit scriptNameChanged(*iter);
-                emit dataChanged(index, index, {Qt::DisplayRole, Qt::EditRole});
-            }
-            return true;
-        default:
-            qWarning() << "unexpected role" << role;
-            return false;
-        }
-    }
-    case NodeType::Font:
-    {
-        if (!m_project)
-        {
-            qWarning() << "unexpected null project";
-            return {};
-        }
-
-        if (index.row() < 0 || index.row() >= m_project->fonts.size())
-        {
-            qWarning() << "unexpected font row" << index.row();
-            return false;
-        }
-        auto iter = std::next(std::begin(m_project->fonts), index.row());
-        switch (role)
-        {
-        case Qt::DisplayRole:
-        case Qt::EditRole:
-            if (auto name = value.toString(); name != iter->name)
-            {
-                if (std::any_of(std::cbegin(m_project->sprites), std::cend(m_project->sprites),
-                                [&name](const auto &entry){ return entry.name == name; }))
-                {
-                    qWarning() << "duplicate name" << name;
-                    emit errorOccured(tr("A Font with the name \"%0\" is already existing").arg(name));
-                    return false;
-                }
-                iter->name = std::move(name);
-                emit fontNameChanged(*iter);
-                emit dataChanged(index, index, {Qt::DisplayRole, Qt::EditRole});
-            }
-            return true;
-        default:
-            qWarning() << "unexpected role" << role;
-            return false;
-        }
-    }
+    case NodeType::Sprite:     return setDataFor<Sprite>(index, value, role);
+    case NodeType::Sound:      return setDataFor<Sound>(index, value, role);
+    case NodeType::Background: return setDataFor<Background>(index, value, role);
+    case NodeType::Path:       return setDataFor<Path>(index, value, role);
+    case NodeType::Script:     return setDataFor<Script>(index, value, role);
+    case NodeType::Font:       return setDataFor<Font>(index, value, role);
+    case NodeType::TimeLine:   return setDataFor<TimeLine>(index, value, role);
+    case NodeType::Object:     return setDataFor<Object>(index, value, role);
+    case NodeType::Room:       return setDataFor<Room>(index, value, role);
     default:
         qWarning() << "unexpected nodeType" << std::to_underlying(nodeType);
         return false;
@@ -674,362 +304,34 @@ bool ProjectTreeModel::moveRows(const QModelIndex &sourceParent, int sourceRow,
 
 bool ProjectTreeModel::insertRows(int row, int count, const QModelIndex &parent)
 {
-    if (parent == spritesRoot())
-    {
-        if (!m_project)
-        {
-            qWarning() << "unexpected null project";
-            return {};
-        }
+    if (auto result = insertRowsFor<Sprite>(row, count, parent))     return *result;
+    if (auto result = insertRowsFor<Sound>(row, count, parent))      return *result;
+    if (auto result = insertRowsFor<Background>(row, count, parent)) return *result;
+    if (auto result = insertRowsFor<Path>(row, count, parent))       return *result;
+    if (auto result = insertRowsFor<Script>(row, count, parent))     return *result;
+    if (auto result = insertRowsFor<Font>(row, count, parent))       return *result;
+    if (auto result = insertRowsFor<TimeLine>(row, count, parent))   return *result;
+    if (auto result = insertRowsFor<Object>(row, count, parent))     return *result;
+    if (auto result = insertRowsFor<Room>(row, count, parent))       return *result;
 
-        if (row < 0 || row > m_project->sprites.size())
-        {
-            qWarning() << "unexpected sprite row" << row;
-            return false;
-        }
-
-        QString name;
-        for (int i = 0; ; i++)
-        {
-            name = QStringLiteral("sprite%0").arg(i);
-            if (std::none_of(std::cbegin(m_project->sprites), std::cend(m_project->sprites),
-                             [&name](const Sprite &sprite){ return sprite.name == name; }))
-                break;
-        }
-
-        emit beginInsertRows(parent, row, row + count - 1);
-        m_project->sprites.emplace(std::next(std::begin(m_project->sprites), row), Sprite { .name = std::move(name) });
-        emit endInsertRows();
-
-        return true;
-    }
-    else if (parent == soundsRoot())
-    {
-        if (!m_project)
-        {
-            qWarning() << "unexpected null project";
-            return {};
-        }
-
-        if (row < 0 || row > m_project->sounds.size())
-        {
-            qWarning() << "unexpected sound row" << row;
-            return false;
-        }
-
-        QString name;
-        for (int i = 0; ; i++)
-        {
-            name = QStringLiteral("sound%0").arg(i);
-            if (std::none_of(std::cbegin(m_project->sounds), std::cend(m_project->sounds),
-                             [&name](const Sound &sound){ return sound.name == name; }))
-                break;
-        }
-
-        emit beginInsertRows(parent, row, row + count - 1);
-        m_project->sounds.emplace(std::next(std::begin(m_project->sounds), row), Sound { .name = std::move(name) });
-        emit endInsertRows();
-
-        return true;
-    }
-    else if (parent == backgroundsRoot())
-    {
-        if (!m_project)
-        {
-            qWarning() << "unexpected null project";
-            return {};
-        }
-
-        if (row < 0 || row > m_project->backgrounds.size())
-        {
-            qWarning() << "unexpected background row" << row;
-            return false;
-        }
-
-        QString name;
-        for (int i = 0; ; i++)
-        {
-            name = QStringLiteral("background%0").arg(i);
-            if (std::none_of(std::cbegin(m_project->backgrounds), std::cend(m_project->backgrounds),
-                             [&name](const Background &background){ return background.name == name; }))
-                break;
-        }
-
-        emit beginInsertRows(parent, row, row + count - 1);
-        m_project->backgrounds.emplace(std::next(std::begin(m_project->backgrounds), row), Background { .name = std::move(name) });
-        emit endInsertRows();
-
-        return true;
-    }
-    else if (parent == pathsRoot())
-    {
-        if (!m_project)
-        {
-            qWarning() << "unexpected null project";
-            return {};
-        }
-
-        if (row < 0 || row > m_project->paths.size())
-        {
-            qWarning() << "unexpected path row" << row;
-            return false;
-        }
-
-        QString name;
-        for (int i = 0; ; i++)
-        {
-            name = QStringLiteral("path%0").arg(i);
-            if (std::none_of(std::cbegin(m_project->paths), std::cend(m_project->paths),
-                             [&name](const Path &path){ return path.name == name; }))
-                break;
-        }
-
-        emit beginInsertRows(parent, row, row + count - 1);
-        m_project->paths.emplace(std::next(std::begin(m_project->paths), row), Path { .name = std::move(name) });
-        emit endInsertRows();
-
-        return true;
-    }
-    else if (parent == scriptsRoot())
-    {
-        if (!m_project)
-        {
-            qWarning() << "unexpected null project";
-            return {};
-        }
-
-        if (row < 0 || row > m_project->scripts.size())
-        {
-            qWarning() << "unexpected script row" << row;
-            return false;
-        }
-
-        QString name;
-        for (int i = 0; ; i++)
-        {
-            name = QStringLiteral("script%0").arg(i);
-            if (std::none_of(std::cbegin(m_project->scripts), std::cend(m_project->scripts),
-                             [&name](const Script &script){ return script.name == name; }))
-                break;
-        }
-
-        emit beginInsertRows(parent, row, row + count - 1);
-        m_project->scripts.emplace(std::next(std::begin(m_project->scripts), row), Script { .name = std::move(name) });
-        emit endInsertRows();
-
-        return true;
-    }
-    else if (parent == fontsRoot())
-    {
-        if (!m_project)
-        {
-            qWarning() << "unexpected null project";
-            return {};
-        }
-
-        if (row < 0 || row > m_project->scripts.size())
-        {
-            qWarning() << "unexpected script row" << row;
-            return false;
-        }
-
-        QString name;
-        for (int i = 0; ; i++)
-        {
-            name = QStringLiteral("font%0").arg(i);
-            if (std::none_of(std::cbegin(m_project->fonts), std::cend(m_project->fonts),
-                             [&name](const Font &font){ return font.name == name; }))
-                break;
-        }
-
-        emit beginInsertRows(parent, row, row + count - 1);
-        m_project->fonts.emplace(std::next(std::begin(m_project->fonts), row), Font { .name = std::move(name) });
-        emit endInsertRows();
-
-        return true;
-    }
-    else
-    {
-        qWarning() << "unexpected parent" << parent;
-        return false;
-    }
+    qWarning() << "unexpected parent" << parent;
+    return false;
 }
 
 bool ProjectTreeModel::removeRows(int row, int count, const QModelIndex &parent)
 {
-    if (parent == spritesRoot())
-    {
-        if (!m_project)
-        {
-            qWarning() << "unexpected null project";
-            return {};
-        }
+    if (auto result = removeRowsFor<Sprite>(row, count, parent))     return *result;
+    if (auto result = removeRowsFor<Sound>(row, count, parent))      return *result;
+    if (auto result = removeRowsFor<Background>(row, count, parent)) return *result;
+    if (auto result = removeRowsFor<Path>(row, count, parent))       return *result;
+    if (auto result = removeRowsFor<Script>(row, count, parent))     return *result;
+    if (auto result = removeRowsFor<Font>(row, count, parent))       return *result;
+    if (auto result = removeRowsFor<TimeLine>(row, count, parent))   return *result;
+    if (auto result = removeRowsFor<Object>(row, count, parent))     return *result;
+    if (auto result = removeRowsFor<Room>(row, count, parent))       return *result;
 
-        if (row < 0 || row >= m_project->sprites.size())
-        {
-            qWarning() << "unexpected sprite row" << row;
-            return false;
-        }
-
-        if (count < 0 || count > m_project->sprites.size() - row)
-        {
-            qWarning() << "unexpected sprite row+count" << count << row;
-            return false;
-        }
-
-        emit beginRemoveRows(parent, row, row + count - 1);
-        auto begin = std::next(std::begin(m_project->sprites), row);
-        auto end = std::next(begin, count);
-        m_project->sprites.erase(begin, end);
-        emit endRemoveRows();
-
-        return true;
-    }
-    else if (parent == soundsRoot())
-    {
-        if (!m_project)
-        {
-            qWarning() << "unexpected null project";
-            return {};
-        }
-
-        if (row < 0 || row >= m_project->sounds.size())
-        {
-            qWarning() << "unexpected sound row" << row;
-            return false;
-        }
-
-        if (count < 0 || count > m_project->sounds.size() - row)
-        {
-            qWarning() << "unexpected sound row+count" << count << row;
-            return false;
-        }
-
-        emit beginRemoveRows(parent, row, row + count - 1);
-        auto begin = std::next(std::begin(m_project->sounds), row);
-        auto end = std::next(begin, count);
-        m_project->sounds.erase(begin, end);
-        emit endRemoveRows();
-
-        return true;
-    }
-    else if (parent == backgroundsRoot())
-    {
-        if (!m_project)
-        {
-            qWarning() << "unexpected null project";
-            return {};
-        }
-
-        if (row < 0 || row >= m_project->backgrounds.size())
-        {
-            qWarning() << "unexpected background row" << row;
-            return false;
-        }
-
-        if (count < 0 || count > m_project->backgrounds.size() - row)
-        {
-            qWarning() << "unexpected background row+count" << count << row;
-            return false;
-        }
-
-        emit beginRemoveRows(parent, row, row + count - 1);
-        auto begin = std::next(std::begin(m_project->backgrounds), row);
-        auto end = std::next(begin, count);
-        m_project->backgrounds.erase(begin, end);
-        emit endRemoveRows();
-
-        return true;
-    }
-    else if (parent == pathsRoot())
-    {
-        if (!m_project)
-        {
-            qWarning() << "unexpected null project";
-            return {};
-        }
-
-        if (row < 0 || row >= m_project->paths.size())
-        {
-            qWarning() << "unexpected path row" << row;
-            return false;
-        }
-
-        if (count < 0 || count > m_project->paths.size() - row)
-        {
-            qWarning() << "unexpected path row+count" << count << row;
-            return false;
-        }
-
-        emit beginRemoveRows(parent, row, row + count - 1);
-        auto begin = std::next(std::begin(m_project->paths), row);
-        auto end = std::next(begin, count);
-        m_project->paths.erase(begin, end);
-        emit endRemoveRows();
-
-        return true;
-    }
-    else if (parent == scriptsRoot())
-    {
-        if (!m_project)
-        {
-            qWarning() << "unexpected null project";
-            return {};
-        }
-
-        if (row < 0 || row >= m_project->scripts.size())
-        {
-            qWarning() << "unexpected script row" << row;
-            return false;
-        }
-
-        if (count < 0 || count > m_project->scripts.size() - row)
-        {
-            qWarning() << "unexpected script row+count" << count << row;
-            return false;
-        }
-
-        emit beginRemoveRows(parent, row, row + count - 1);
-        auto begin = std::next(std::begin(m_project->scripts), row);
-        auto end = std::next(begin, count);
-        m_project->scripts.erase(begin, end);
-        emit endRemoveRows();
-
-        return true;
-    }
-    else if (parent == fontsRoot())
-    {
-        if (!m_project)
-        {
-            qWarning() << "unexpected null project";
-            return {};
-        }
-
-        if (row < 0 || row >= m_project->fonts.size())
-        {
-            qWarning() << "unexpected font row" << row;
-            return false;
-        }
-
-        if (count < 0 || count > m_project->fonts.size() - row)
-        {
-            qWarning() << "unexpected font row+count" << count << row;
-            return false;
-        }
-
-        emit beginRemoveRows(parent, row, row + count - 1);
-        auto begin = std::next(std::begin(m_project->fonts), row);
-        auto end = std::next(begin, count);
-        m_project->fonts.erase(begin, end);
-        emit endRemoveRows();
-
-        return true;
-    }
-    else
-    {
-        qWarning() << "unexpected parent" << parent;
-        return false;
-    }
+    qWarning() << "unexpected parent" << parent;
+    return false;
 }
 
 Qt::DropActions ProjectTreeModel::supportedDragActions() const
@@ -1057,47 +359,47 @@ ProjectTreeModel::NodeType ProjectTreeModel::nodeType(const QModelIndex &index)
     return NodeType(index.internalId());
 }
 
-QModelIndex ProjectTreeModel::spritesRoot() const
+template<> QModelIndex ProjectTreeModel::rootFor<Sprite>() const
 {
-    return createIndex(RowSprites, 0,     std::to_underlying(NodeType::Root));
+    return createIndex(RowSprites, 0, std::to_underlying(NodeType::Root));
 }
 
-QModelIndex ProjectTreeModel::soundsRoot() const
+template<> QModelIndex ProjectTreeModel::rootFor<Sound>() const
 {
-    return createIndex(RowSounds, 0,      std::to_underlying(NodeType::Root));
+    return createIndex(RowSounds, 0, std::to_underlying(NodeType::Root));
 }
 
-QModelIndex ProjectTreeModel::backgroundsRoot() const
+template<> QModelIndex ProjectTreeModel::rootFor<Background>() const
 {
     return createIndex(RowBackgrounds, 0, std::to_underlying(NodeType::Root));
 }
 
-QModelIndex ProjectTreeModel::pathsRoot() const
+template<> QModelIndex ProjectTreeModel::rootFor<Path>() const
 {
     return createIndex(RowPaths, 0, std::to_underlying(NodeType::Root));
 }
 
-QModelIndex ProjectTreeModel::scriptsRoot() const
+template<> QModelIndex ProjectTreeModel::rootFor<Script>() const
 {
     return createIndex(RowScripts, 0, std::to_underlying(NodeType::Root));
 }
 
-QModelIndex ProjectTreeModel::fontsRoot() const
+template<> QModelIndex ProjectTreeModel::rootFor<Font>() const
 {
     return createIndex(RowFonts, 0, std::to_underlying(NodeType::Root));
 }
 
-QModelIndex ProjectTreeModel::timeLinesRoot() const
+template<> QModelIndex ProjectTreeModel::rootFor<TimeLine>() const
 {
     return createIndex(RowTimeLines, 0, std::to_underlying(NodeType::Root));
 }
 
-QModelIndex ProjectTreeModel::objectsRoot() const
+template<> QModelIndex ProjectTreeModel::rootFor<Object>() const
 {
     return createIndex(RowObjects, 0, std::to_underlying(NodeType::Root));
 }
 
-QModelIndex ProjectTreeModel::roomsRoot() const
+template<> QModelIndex ProjectTreeModel::rootFor<Room>() const
 {
     return createIndex(RowRooms, 0, std::to_underlying(NodeType::Root));
 }
@@ -1117,7 +419,8 @@ QModelIndex ProjectTreeModel::extensionPackagesRoot() const
     return createIndex(RowExtensionPackages, 0, std::to_underlying(NodeType::Root));
 }
 
-Sprite *ProjectTreeModel::getSprite(const QModelIndex &index)
+template<typename T>
+T *ProjectTreeModel::get(const QModelIndex &index)
 {
     if (!m_project)
     {
@@ -1125,28 +428,24 @@ Sprite *ProjectTreeModel::getSprite(const QModelIndex &index)
         return {};
     }
 
-    if (const auto nodeType = this->nodeType(index); nodeType != NodeType::Sprite)
+    if (const auto nodeType = this->nodeType(index); nodeType != nodeTypeFor<T>())
     {
         qWarning() << "unexpected index type" << std::to_underlying(nodeType);
         return nullptr;
     }
 
-    if (index.row() < 0)
+    auto &container = m_project->containerFor<T>();
+    if (index.row() < 0 || index.row() >= container.size())
     {
-        qWarning() << "unexpected negative row" << index.row();
+        qWarning() << "invalid row" << index.row();
         return nullptr;
     }
 
-    if (index.row() >= m_project->sprites.size())
-    {
-        qWarning() << "sprite index out of bounds" << index.row();
-        return {};
-    }
-
-    return &*std::next(std::begin(m_project->sprites), index.row());
+    return &*std::next(std::begin(container), index.row());
 }
 
-const Sprite *ProjectTreeModel::getSprite(const QModelIndex &index) const
+template<typename T>
+const T *ProjectTreeModel::get(const QModelIndex &index) const
 {
     if (!m_project)
     {
@@ -1154,487 +453,406 @@ const Sprite *ProjectTreeModel::getSprite(const QModelIndex &index) const
         return {};
     }
 
-    if (const auto nodeType = this->nodeType(index); nodeType != NodeType::Sprite)
+    if (const auto nodeType = this->nodeType(index); nodeType != nodeTypeFor<T>())
     {
         qWarning() << "unexpected index type" << std::to_underlying(nodeType);
         return nullptr;
     }
 
-    if (index.row() < 0)
+    const auto &container = m_project->containerFor<T>();
+    if (index.row() < 0 || index.row() >= container.size())
     {
-        qWarning() << "unexpected negative row" << index.row();
+        qWarning() << "invalid row" << index.row();
         return nullptr;
     }
 
-    if (index.row() >= m_project->sprites.size())
-    {
-        qWarning() << "sprite index out of bounds" << index.row();
-        return {};
-    }
-
-    return &*std::next(std::cbegin(m_project->sprites), index.row());
+    return &*std::next(std::cbegin(container), index.row());
 }
 
-Sound *ProjectTreeModel::getSound(const QModelIndex &index)
+template Sprite *ProjectTreeModel::get<Sprite>(const QModelIndex &index);
+template const Sprite *ProjectTreeModel::get<Sprite>(const QModelIndex &index) const;
+template Sound *ProjectTreeModel::get<Sound>(const QModelIndex &index);
+template const Sound *ProjectTreeModel::get<Sound>(const QModelIndex &index) const;
+template Background *ProjectTreeModel::get<Background>(const QModelIndex &index);
+template const Background *ProjectTreeModel::get<Background>(const QModelIndex &index) const;
+template Path *ProjectTreeModel::get<Path>(const QModelIndex &index);
+template const Path *ProjectTreeModel::get<Path>(const QModelIndex &index) const;
+template Script *ProjectTreeModel::get<Script>(const QModelIndex &index);
+template const Script *ProjectTreeModel::get<Script>(const QModelIndex &index) const;
+template Font *ProjectTreeModel::get<Font>(const QModelIndex &index);
+template const Font *ProjectTreeModel::get<Font>(const QModelIndex &index) const;
+template TimeLine *ProjectTreeModel::get<TimeLine>(const QModelIndex &index);
+template const TimeLine *ProjectTreeModel::get<TimeLine>(const QModelIndex &index) const;
+template Object *ProjectTreeModel::get<Object>(const QModelIndex &index);
+template const Object *ProjectTreeModel::get<Object>(const QModelIndex &index) const;
+template Room *ProjectTreeModel::get<Room>(const QModelIndex &index);
+template const Room *ProjectTreeModel::get<Room>(const QModelIndex &index) const;
+
+template<typename T>
+bool ProjectTreeModel::rename(const T &entry, const QString &newName)
 {
-    if (!m_project)
+    auto &container = m_project->containerFor<T>();
+    const auto iter = std::find_if(std::begin(container), std::end(container),
+                                   [&entry](const auto &otherEntry){ return &entry == &otherEntry; });
+    if (iter == std::cend(container))
     {
-        qWarning() << "unexpected null project";
-        return {};
-    }
-
-    if (const auto nodeType = this->nodeType(index); nodeType != NodeType::Sound)
-    {
-        qWarning() << "unexpected index type" << std::to_underlying(nodeType);
-        return nullptr;
-    }
-
-    if (index.row() < 0)
-    {
-        qWarning() << "unexpected negative row" << index.row();
-        return nullptr;
-    }
-
-    if (index.row() >= m_project->sounds.size())
-    {
-        qWarning() << "sound index out of bounds" << index.row();
-        return {};
-    }
-
-    return &*std::next(std::begin(m_project->sounds), index.row());
-}
-
-const Sound *ProjectTreeModel::getSound(const QModelIndex &index) const
-{
-    if (!m_project)
-    {
-        qWarning() << "unexpected null project";
-        return {};
-    }
-
-    if (const auto nodeType = this->nodeType(index); nodeType != NodeType::Sound)
-    {
-        qWarning() << "unexpected index type" << std::to_underlying(nodeType);
-        return nullptr;
-    }
-
-    if (index.row() < 0)
-    {
-        qWarning() << "unexpected negative row" << index.row();
-        return nullptr;
-    }
-
-    if (index.row() >= m_project->sounds.size())
-    {
-        qWarning() << "sound index out of bounds" << index.row();
-        return {};
-    }
-
-    return &*std::next(std::cbegin(m_project->sounds), index.row());
-}
-
-Background *ProjectTreeModel::getBackground(const QModelIndex &index)
-{
-    if (!m_project)
-    {
-        qWarning() << "unexpected null project";
-        return {};
-    }
-
-    if (const auto nodeType = this->nodeType(index); nodeType != NodeType::Background)
-    {
-        qWarning() << "unexpected index type" << std::to_underlying(nodeType);
-        return nullptr;
-    }
-
-    if (index.row() < 0)
-    {
-        qWarning() << "unexpected negative row" << index.row();
-        return nullptr;
-    }
-
-    if (index.row() >= m_project->backgrounds.size())
-    {
-        qWarning() << "background index out of bounds" << index.row();
-        return {};
-    }
-
-    return &*std::next(std::begin(m_project->backgrounds), index.row());
-}
-
-const Background *ProjectTreeModel::getBackground(const QModelIndex &index) const
-{
-    if (!m_project)
-    {
-        qWarning() << "unexpected null project";
-        return {};
-    }
-
-    if (const auto nodeType = this->nodeType(index); nodeType != NodeType::Background)
-    {
-        qWarning() << "unexpected index type" << std::to_underlying(nodeType);
-        return nullptr;
-    }
-
-    if (index.row() < 0)
-    {
-        qWarning() << "unexpected negative row" << index.row();
-        return nullptr;
-    }
-
-    if (index.row() >= m_project->backgrounds.size())
-    {
-        qWarning() << "background index out of bounds" << index.row();
-        return {};
-    }
-
-    return &*std::next(std::cbegin(m_project->backgrounds), index.row());
-}
-
-Path *ProjectTreeModel::getPath(const QModelIndex &index)
-{
-    if (!m_project)
-    {
-        qWarning() << "unexpected null project";
-        return {};
-    }
-
-    if (const auto nodeType = this->nodeType(index); nodeType != NodeType::Path)
-    {
-        qWarning() << "unexpected index type" << std::to_underlying(nodeType);
-        return nullptr;
-    }
-
-    if (index.row() < 0)
-    {
-        qWarning() << "unexpected negative row" << index.row();
-        return nullptr;
-    }
-
-    if (index.row() >= m_project->paths.size())
-    {
-        qWarning() << "path index out of bounds" << index.row();
-        return {};
-    }
-
-    return &*std::next(std::begin(m_project->paths), index.row());
-}
-
-const Path *ProjectTreeModel::getPath(const QModelIndex &index) const
-{
-    if (!m_project)
-    {
-        qWarning() << "unexpected null project";
-        return {};
-    }
-
-    if (const auto nodeType = this->nodeType(index); nodeType != NodeType::Path)
-    {
-        qWarning() << "unexpected index type" << std::to_underlying(nodeType);
-        return nullptr;
-    }
-
-    if (index.row() < 0)
-    {
-        qWarning() << "unexpected negative row" << index.row();
-        return nullptr;
-    }
-
-    if (index.row() >= m_project->paths.size())
-    {
-        qWarning() << "path index out of bounds" << index.row();
-        return {};
-    }
-
-    return &*std::next(std::cbegin(m_project->paths), index.row());
-}
-
-Script *ProjectTreeModel::getScript(const QModelIndex &index)
-{
-    if (!m_project)
-    {
-        qWarning() << "unexpected null project";
-        return {};
-    }
-
-    if (const auto nodeType = this->nodeType(index); nodeType != NodeType::Script)
-    {
-        qWarning() << "unexpected index type" << std::to_underlying(nodeType);
-        return nullptr;
-    }
-
-    if (index.row() < 0)
-    {
-        qWarning() << "unexpected negative row" << index.row();
-        return nullptr;
-    }
-
-    if (index.row() >= m_project->scripts.size())
-    {
-        qWarning() << "script index out of bounds" << index.row();
-        return {};
-    }
-
-    return &*std::next(std::begin(m_project->scripts), index.row());
-}
-
-const Script *ProjectTreeModel::getScript(const QModelIndex &index) const
-{
-    if (!m_project)
-    {
-        qWarning() << "unexpected null project";
-        return {};
-    }
-
-    if (const auto nodeType = this->nodeType(index); nodeType != NodeType::Script)
-    {
-        qWarning() << "unexpected index type" << std::to_underlying(nodeType);
-        return nullptr;
-    }
-
-    if (index.row() < 0)
-    {
-        qWarning() << "unexpected negative row" << index.row();
-        return nullptr;
-    }
-
-    if (index.row() >= m_project->scripts.size())
-    {
-        qWarning() << "script index out of bounds" << index.row();
-        return {};
-    }
-
-    return &*std::next(std::cbegin(m_project->scripts), index.row());
-}
-
-Font *ProjectTreeModel::getFont(const QModelIndex &index)
-{
-    if (!m_project)
-    {
-        qWarning() << "unexpected null project";
-        return {};
-    }
-
-    if (const auto nodeType = this->nodeType(index); nodeType != NodeType::Font)
-    {
-        qWarning() << "unexpected index type" << std::to_underlying(nodeType);
-        return nullptr;
-    }
-
-    if (index.row() < 0)
-    {
-        qWarning() << "unexpected negative row" << index.row();
-        return nullptr;
-    }
-
-    if (index.row() >= m_project->fonts.size())
-    {
-        qWarning() << "font index out of bounds" << index.row();
-        return {};
-    }
-
-    return &*std::next(std::begin(m_project->fonts), index.row());
-}
-
-const Font *ProjectTreeModel::getFont(const QModelIndex &index) const
-{
-    if (!m_project)
-    {
-        qWarning() << "unexpected null project";
-        return {};
-    }
-
-    if (const auto nodeType = this->nodeType(index); nodeType != NodeType::Font)
-    {
-        qWarning() << "unexpected index type" << std::to_underlying(nodeType);
-        return nullptr;
-    }
-
-    if (index.row() < 0)
-    {
-        qWarning() << "unexpected negative row" << index.row();
-        return nullptr;
-    }
-
-    if (index.row() >= m_project->fonts.size())
-    {
-        qWarning() << "font index out of bounds" << index.row();
-        return {};
-    }
-
-    return &*std::next(std::cbegin(m_project->fonts), index.row());
-}
-
-bool ProjectTreeModel::renameSprite(const Sprite &sprite, const QString &newName)
-{
-    const auto iter = std::find_if(std::begin(m_project->sprites), std::end(m_project->sprites),
-                                   [&sprite](const auto &entry){ return &entry == &sprite; });
-    if (iter == std::cend(m_project->sprites))
-    {
-        qWarning() << "sprite not from this project!";
+        qWarning() << "entry not from this project!";
         return false;
     }
 
     if (iter->name == newName)
         return true;
 
-    if (std::any_of(std::cbegin(m_project->sprites), std::cend(m_project->sprites),
+    if (std::any_of(std::cbegin(container), std::cend(container),
                     [&newName](const auto &entry){ return entry.name == newName; }))
     {
-        qWarning() << "duplicate sprite name" << newName;
+        qWarning() << "duplicate name" << newName;
         return false;
     }
 
     iter->name = newName;
 
-    emit spriteNameChanged(*iter);
-    const auto index = this->index(std::distance(std::begin(m_project->sprites), iter), 0, spritesRoot());
+    emitNameChanged<T>(*iter);
+    const auto index = this->index(std::distance(std::begin(container), iter), 0, rootFor<T>());
     emit dataChanged(index, index, {Qt::DisplayRole, Qt::EditRole});
 
     return true;
 }
 
-bool ProjectTreeModel::renameSound(const Sound &sound, const QString &newName)
+template bool ProjectTreeModel::rename<Sprite>(const Sprite &entry, const QString &newName);
+template bool ProjectTreeModel::rename<Sound>(const Sound &entry, const QString &newName);
+template bool ProjectTreeModel::rename<Background>(const Background &entry, const QString &newName);
+template bool ProjectTreeModel::rename<Path>(const Path &entry, const QString &newName);
+template bool ProjectTreeModel::rename<Script>(const Script &entry, const QString &newName);
+template bool ProjectTreeModel::rename<Font>(const Font &entry, const QString &newName);
+template bool ProjectTreeModel::rename<TimeLine>(const TimeLine &entry, const QString &newName);
+template bool ProjectTreeModel::rename<Object>(const Object &entry, const QString &newName);
+template bool ProjectTreeModel::rename<Room>(const Room &entry, const QString &newName);
+
+template<typename T>
+QVariant ProjectTreeModel::dataFor(const QModelIndex &index, int role) const
 {
-    const auto iter = std::find_if(std::begin(m_project->sounds), std::end(m_project->sounds),
-                                   [&sound](const auto &entry){ return &entry == &sound; });
-    if (iter == std::cend(m_project->sounds))
+    if (!m_project)
     {
-        qWarning() << "sound not from this project!";
-        return false;
+        qWarning() << "unexpected null project";
+        return {};
     }
 
-    if (iter->name == newName)
-        return true;
-
-    if (std::any_of(std::cbegin(m_project->sounds), std::cend(m_project->sounds),
-                    [&newName](const auto &entry){ return entry.name == newName; }))
+    const auto &container = m_project->containerFor<T>();
+    if (index.row() >= container.size())
     {
-        qWarning() << "duplicate sound name" << newName;
-        return false;
+        qWarning() << "index out of bounds" << index.row();
+        return {};
     }
 
-    iter->name = newName;
+    auto iter = std::next(std::cbegin(container), index.row());
 
-    emit soundNameChanged(*iter);
-    const auto index = this->index(std::distance(std::begin(m_project->sounds), iter), 0, soundsRoot());
-    emit dataChanged(index, index, {Qt::DisplayRole, Qt::EditRole});
+    switch (role)
+    {
+    case Qt::DisplayRole:
+    case Qt::EditRole:
+        return iter->name;
+    case Qt::DecorationRole:
+        return iconFor<T>(*iter);
 
-    return true;
+    default:
+        return {};
+    }
 }
 
-bool ProjectTreeModel::renameBackground(const Background &background, const QString &newName)
+template<>
+QVariant ProjectTreeModel::iconFor<Sprite>(const Sprite &entry) const
 {
-    const auto iter = std::find_if(std::begin(m_project->backgrounds), std::end(m_project->backgrounds),
-                                   [&background](const auto &entry){ return &entry == &background; });
-    if (iter == std::cend(m_project->backgrounds))
+    if (entry.pixmaps.empty() || entry.pixmaps.front().isNull())
     {
-        qWarning() << "background not from this project!";
-        return false;
+        QPixmap pixmap{16, 16};
+        pixmap.fill(Qt::white);
+        return pixmap;
     }
-
-    if (iter->name == newName)
-        return true;
-
-    if (std::any_of(std::cbegin(m_project->backgrounds), std::cend(m_project->backgrounds),
-                    [&newName](const auto &entry){ return entry.name == newName; }))
-    {
-        qWarning() << "duplicate background name" << newName;
-        return false;
-    }
-
-    iter->name = newName;
-
-    emit backgroundNameChanged(*iter);
-    const auto index = this->index(std::distance(std::begin(m_project->backgrounds), iter), 0, backgroundsRoot());
-    emit dataChanged(index, index, {Qt::DisplayRole, Qt::EditRole});
-
-    return true;
+    return entry.pixmaps.front().scaled(16, 16, Qt::IgnoreAspectRatio /*KeepAspectRatio*/);
 }
 
-bool ProjectTreeModel::renamePath(const Path &path, const QString &newName)
+template<>
+QVariant ProjectTreeModel::iconFor<Sound>(const Sound &entry) const
 {
-    const auto iter = std::find_if(std::begin(m_project->paths), std::end(m_project->paths),
-                                   [&path](const auto &entry){ return &entry == &path; });
-    if (iter == std::cend(m_project->paths))
+    switch (entry.type)
     {
-        qWarning() << "path not from this project!";
-        return false;
+    case Sound::Type::Sound:
+        return QPixmap{":/qtgameengine/icons/sound-file.png"}.scaled(16, 16);
+    case Sound::Type::Music:
+        return QPixmap{":/qtgameengine/icons/music-file.png"}.scaled(16, 16);
+    default:
+        qWarning() << "unexpected sound type" << std::to_underlying(entry.type);
+        return {};
     }
-
-    if (iter->name == newName)
-        return true;
-
-    if (std::any_of(std::cbegin(m_project->paths), std::cend(m_project->paths),
-                    [&newName](const auto &entry){ return entry.name == newName; }))
-    {
-        qWarning() << "duplicate path name" << newName;
-        return false;
-    }
-
-    iter->name = newName;
-
-    emit pathNameChanged(*iter);
-    const auto index = this->index(std::distance(std::begin(m_project->paths), iter), 0, pathsRoot());
-    emit dataChanged(index, index, {Qt::DisplayRole, Qt::EditRole});
-
-    return true;
 }
 
-bool ProjectTreeModel::renameScript(const Script &script, const QString &newName)
+template<>
+QVariant ProjectTreeModel::iconFor<Background>(const Background &entry) const
 {
-    const auto iter = std::find_if(std::begin(m_project->scripts), std::end(m_project->scripts),
-                                   [&script](const auto &entry){ return &entry == &script; });
-    if (iter == std::cend(m_project->scripts))
+    if (entry.pixmap.isNull())
     {
-        qWarning() << "script not from this project!";
-        return false;
+        QPixmap pixmap{16, 16};
+        pixmap.fill(Qt::white);
+        return pixmap;
     }
-
-    if (iter->name == newName)
-        return true;
-
-    if (std::any_of(std::cbegin(m_project->scripts), std::cend(m_project->scripts),
-                    [&newName](const auto &entry){ return entry.name == newName; }))
-    {
-        qWarning() << "duplicate script name" << newName;
-        return false;
-    }
-
-    iter->name = newName;
-
-    emit scriptNameChanged(*iter);
-    const auto index = this->index(std::distance(std::begin(m_project->scripts), iter), 0, scriptsRoot());
-    emit dataChanged(index, index, {Qt::DisplayRole, Qt::EditRole});
-
-    return true;
+    return entry.pixmap.scaled(16, 16, Qt::KeepAspectRatio);
 }
 
-bool ProjectTreeModel::renameFont(const Font &font, const QString &newName)
+template<>
+QVariant ProjectTreeModel::iconFor<Path>(const Path &entry) const
 {
-    const auto iter = std::find_if(std::begin(m_project->fonts), std::end(m_project->fonts),
-                                   [&font](const auto &entry){ return &entry == &font; });
-    if (iter == std::cend(m_project->fonts))
-    {
-        qWarning() << "font not from this project!";
-        return false;
-    }
-
-    if (iter->name == newName)
-        return true;
-
-    if (std::any_of(std::cbegin(m_project->fonts), std::cend(m_project->fonts),
-                    [&newName](const auto &entry){ return entry.name == newName; }))
-    {
-        qWarning() << "duplicate font name" << newName;
-        return false;
-    }
-
-    iter->name = newName;
-
-    emit fontNameChanged(*iter);
-    const auto index = this->index(std::distance(std::begin(m_project->fonts), iter), 0, fontsRoot());
-    emit dataChanged(index, index, {Qt::DisplayRole, Qt::EditRole});
-
-    return true;
+    return QPixmap{":/qtgameengine/icons/path-file.png"}.scaled(16, 16);
+}
+
+template<>
+QVariant ProjectTreeModel::iconFor<Script>(const Script &entry) const
+{
+    return QPixmap{":/qtgameengine/icons/script-file.png"}.scaled(16, 16);
+}
+
+template<>
+QVariant ProjectTreeModel::iconFor<Font>(const Font &entry) const
+{
+    return QPixmap{":/qtgameengine/icons/font-file.png"}.scaled(16, 16);
+}
+
+template<>
+QVariant ProjectTreeModel::iconFor<TimeLine>(const TimeLine &entry) const
+{
+    return QPixmap{":/qtgameengine/icons/timeline-file.png"}.scaled(16, 16);
+}
+
+template<>
+QVariant ProjectTreeModel::iconFor<Object>(const Object &entry) const
+{
+    return QPixmap{":/qtgameengine/icons/object-file.png"}.scaled(16, 16);
+}
+
+template<>
+QVariant ProjectTreeModel::iconFor<Room>(const Room &entry) const
+{
+    return QPixmap{":/qtgameengine/icons/room-file.png"}.scaled(16, 16);
+}
+
+template<typename T>
+bool ProjectTreeModel::setDataFor(const QModelIndex &index, const QVariant &value, int role)
+{
+    if (!m_project)
+    {
+        qWarning() << "unexpected null project";
+        return {};
+    }
+
+    auto &container = m_project->containerFor<T>();
+    if (index.row() < 0 || index.row() >= container.size())
+    {
+        qWarning() << "unexpected row" << index.row();
+        return false;
+    }
+    auto iter = std::next(std::begin(container), index.row());
+    switch (role)
+    {
+    case Qt::DisplayRole:
+    case Qt::EditRole:
+        if (auto name = value.toString(); name != iter->name)
+        {
+            if (std::any_of(std::cbegin(container), std::cend(container),
+                            [&name](const auto &entry){ return entry.name == name; }))
+            {
+                qWarning() << "duplicate name" << name;
+                emit errorOccured(tr("A Sprite with the name \"%0\" is already existing").arg(name));
+                return false;
+            }
+            iter->name = std::move(name);
+            emitNameChanged<T>(*iter);
+            emit dataChanged(index, index, {Qt::DisplayRole, Qt::EditRole});
+        }
+        return true;
+    default:
+        qWarning() << "unexpected role" << role;
+        return false;
+    }
+}
+
+template<typename T>
+std::optional<bool> ProjectTreeModel::insertRowsFor(int row, int count, const QModelIndex &parent)
+{
+    if (parent == rootFor<T>())
+    {
+        if (!m_project)
+        {
+            qWarning() << "unexpected null project";
+            return {};
+        }
+
+        auto &container = m_project->containerFor<T>();
+        if (row < 0 || row > container.size())
+        {
+            qWarning() << "unexpected row" << row;
+            return false;
+        }
+
+        QString name;
+        for (int i = 0; ; i++)
+        {
+            name = nameTempateFor<T>().arg(i);
+            if (std::none_of(std::cbegin(container), std::cend(container),
+                             [&name](const T &entry){ return entry.name == name; }))
+                break;
+        }
+
+        emit beginInsertRows(parent, row, row + count - 1);
+        container.emplace(std::next(std::begin(container), row), T { .name = std::move(name) });
+        emit endInsertRows();
+
+        return true;
+    }
+
+    return std::nullopt;
+}
+
+template<typename T>
+std::optional<bool> ProjectTreeModel::removeRowsFor(int row, int count, const QModelIndex &parent)
+{
+    if (parent == rootFor<T>())
+    {
+        if (!m_project)
+        {
+            qWarning() << "unexpected null project";
+            return false;
+        }
+
+        auto &container = m_project->containerFor<T>();
+
+        if (row < 0 || row >= container.size())
+        {
+            qWarning() << "unexpected row" << row;
+            return false;
+        }
+
+        if (count < 0 || count > container.size() - row)
+        {
+            qWarning() << "unexpected row+count" << count << row;
+            return false;
+        }
+
+        emit beginRemoveRows(parent, row, row + count - 1);
+        auto begin = std::next(std::begin(container), row);
+        auto end = std::next(begin, count);
+        container.erase(begin, end);
+        emit endRemoveRows();
+
+        return true;
+    }
+
+    return std::nullopt;
+}
+
+template<>
+void ProjectTreeModel::emitNameChanged<Sprite>(const Sprite &entry)
+{
+    emit spriteNameChanged(entry);
+}
+
+template<>
+void ProjectTreeModel::emitNameChanged<Sound>(const Sound &entry)
+{
+    emit soundNameChanged(entry);
+}
+
+template<>
+void ProjectTreeModel::emitNameChanged<Background>(const Background &entry)
+{
+    emit backgroundNameChanged(entry);
+}
+
+template<>
+void ProjectTreeModel::emitNameChanged<Path>(const Path &entry)
+{
+    emit pathNameChanged(entry);
+}
+
+template<>
+void ProjectTreeModel::emitNameChanged<Script>(const Script &entry)
+{
+    emit scriptNameChanged(entry);
+}
+
+template<>
+void ProjectTreeModel::emitNameChanged<Font>(const Font &entry)
+{
+    emit fontNameChanged(entry);
+}
+
+template<>
+void ProjectTreeModel::emitNameChanged<TimeLine>(const TimeLine &entry)
+{
+    emit timeLineNameChanged(entry);
+}
+
+template<>
+void ProjectTreeModel::emitNameChanged<Object>(const Object &entry)
+{
+    emit objectNameChanged(entry);
+}
+
+template<>
+void ProjectTreeModel::emitNameChanged<Room>(const Room &entry)
+{
+    emit roomNameChanged(entry);
+}
+
+template<>
+QString ProjectTreeModel::nameTempateFor<Sprite>()
+{
+    return QStringLiteral("sprite%0");
+}
+
+template<>
+QString ProjectTreeModel::nameTempateFor<Sound>()
+{
+    return QStringLiteral("sound%0");
+}
+
+template<>
+QString ProjectTreeModel::nameTempateFor<Background>()
+{
+    return QStringLiteral("background%0");
+}
+
+template<>
+QString ProjectTreeModel::nameTempateFor<Path>()
+{
+    return QStringLiteral("path%0");
+}
+
+template<>
+QString ProjectTreeModel::nameTempateFor<Script>()
+{
+    return QStringLiteral("script%0");
+}
+
+template<>
+QString ProjectTreeModel::nameTempateFor<Font>()
+{
+    return QStringLiteral("font%0");
+}
+
+template<>
+QString ProjectTreeModel::nameTempateFor<TimeLine>()
+{
+    return QStringLiteral("timeline%0");
+}
+
+template<>
+QString ProjectTreeModel::nameTempateFor<Object>()
+{
+    return QStringLiteral("object%0");
+}
+
+template<>
+QString ProjectTreeModel::nameTempateFor<Room>()
+{
+    return QStringLiteral("room%0");
 }
diff --git a/projecttreemodel.h b/projecttreemodel.h
index 7f93e08..5569de4 100644
--- a/projecttreemodel.h
+++ b/projecttreemodel.h
@@ -2,6 +2,8 @@
 
 #include <QAbstractItemModel>
 
+#include <optional>
+
 struct ProjectContainer;
 struct Sprite;
 struct Sound;
@@ -9,6 +11,9 @@ struct Background;
 struct Path;
 struct Script;
 struct Font;
+struct TimeLine;
+struct Object;
+struct Room;
 
 class ProjectTreeModel : public QAbstractItemModel
 {
@@ -23,6 +28,9 @@ public:
         Path,
         Script,
         Font,
+        TimeLine,
+        Object,
+        Room,
     };
 
     explicit ProjectTreeModel(QObject *parent = nullptr);
@@ -44,43 +52,18 @@ public:
     void setProject(ProjectContainer *project);
     NodeType nodeType(const QModelIndex &index) const;
 
-    QModelIndex spritesRoot() const;
-    QModelIndex soundsRoot() const;
-    QModelIndex backgroundsRoot() const;
-    QModelIndex pathsRoot() const;
-    QModelIndex scriptsRoot() const;
-    QModelIndex fontsRoot() const;
-    QModelIndex timeLinesRoot() const;
-    QModelIndex objectsRoot() const;
-    QModelIndex roomsRoot() const;
+    template<typename T> QModelIndex rootFor() const;
+
     QModelIndex gameInformationRoot() const;
     QModelIndex globalGameSettingsRoot() const;
     QModelIndex extensionPackagesRoot() const;
 
-    Sprite *getSprite(const QModelIndex &index);
-    const Sprite *getSprite(const QModelIndex &index) const;
+    template<typename T> T *get(const QModelIndex &index);
+    template<typename T> const T *get(const QModelIndex &index) const;
 
-    Sound *getSound(const QModelIndex &index);
-    const Sound *getSound(const QModelIndex &index) const;
+    template<typename T> bool rename(const T &sprite, const QString &newName);
 
-    Background *getBackground(const QModelIndex &index);
-    const Background *getBackground(const QModelIndex &index) const;
-
-    Path *getPath(const QModelIndex &index);
-    const Path *getPath(const QModelIndex &index) const;
-
-    Script *getScript(const QModelIndex &index);
-    const Script *getScript(const QModelIndex &index) const;
-
-    Font *getFont(const QModelIndex &index);
-    const Font *getFont(const QModelIndex &index) const;
-
-    bool renameSprite(const Sprite &sprite, const QString &newName);
-    bool renameSound(const Sound &sound, const QString &newName);
-    bool renameBackground(const Background &background, const QString &newName);
-    bool renamePath(const Path &path, const QString &newName);
-    bool renameScript(const Script &script, const QString &newName);
-    bool renameFont(const Font &font, const QString &newName);
+    template<typename T> static constexpr ProjectTreeModel::NodeType nodeTypeFor() = delete;
 
 signals:
     void errorOccured(const QString &message);
@@ -91,7 +74,67 @@ signals:
     void pathNameChanged(const Path &path);
     void scriptNameChanged(const Script &script);
     void fontNameChanged(const Font &font);
+    void timeLineNameChanged(const TimeLine &font);
+    void objectNameChanged(const Object &font);
+    void roomNameChanged(const Room &font);
 
 private:
+    template<typename T> QVariant dataFor(const QModelIndex &index, int role) const;
+    template<typename T> QVariant iconFor(const T &entry) const;
+    template<typename T> bool setDataFor(const QModelIndex &index, const QVariant &value, int role);
+    template<typename T> std::optional<bool> insertRowsFor(int row, int count, const QModelIndex &parent);
+    template<typename T> std::optional<bool> removeRowsFor(int row, int count, const QModelIndex &parent);
+    template<typename T> void emitNameChanged(const T &entry);
+    template<typename T> static QString nameTempateFor();
+
     ProjectContainer *m_project{};
 };
+
+template<> constexpr ProjectTreeModel::NodeType ProjectTreeModel::nodeTypeFor<Sprite>()     { return ProjectTreeModel::NodeType::Sprite; }
+template<> constexpr ProjectTreeModel::NodeType ProjectTreeModel::nodeTypeFor<Sound>()      { return ProjectTreeModel::NodeType::Sound; }
+template<> constexpr ProjectTreeModel::NodeType ProjectTreeModel::nodeTypeFor<Background>() { return ProjectTreeModel::NodeType::Background; }
+template<> constexpr ProjectTreeModel::NodeType ProjectTreeModel::nodeTypeFor<Path>()       { return ProjectTreeModel::NodeType::Path; }
+template<> constexpr ProjectTreeModel::NodeType ProjectTreeModel::nodeTypeFor<Script>()     { return ProjectTreeModel::NodeType::Script; }
+template<> constexpr ProjectTreeModel::NodeType ProjectTreeModel::nodeTypeFor<Font>()       { return ProjectTreeModel::NodeType::Font; }
+template<> constexpr ProjectTreeModel::NodeType ProjectTreeModel::nodeTypeFor<TimeLine>()   { return ProjectTreeModel::NodeType::TimeLine; }
+template<> constexpr ProjectTreeModel::NodeType ProjectTreeModel::nodeTypeFor<Object>()     { return ProjectTreeModel::NodeType::Object; }
+template<> constexpr ProjectTreeModel::NodeType ProjectTreeModel::nodeTypeFor<Room>()       { return ProjectTreeModel::NodeType::Room; }
+
+template<> QModelIndex ProjectTreeModel::rootFor<Sprite>() const;
+template<> QModelIndex ProjectTreeModel::rootFor<Sound>() const;
+template<> QModelIndex ProjectTreeModel::rootFor<Background>() const;
+template<> QModelIndex ProjectTreeModel::rootFor<Path>() const;
+template<> QModelIndex ProjectTreeModel::rootFor<Script>() const;
+template<> QModelIndex ProjectTreeModel::rootFor<Font>() const;
+template<> QModelIndex ProjectTreeModel::rootFor<TimeLine>() const;
+template<> QModelIndex ProjectTreeModel::rootFor<Object>() const;
+template<> QModelIndex ProjectTreeModel::rootFor<Room>() const;
+
+//template<> Sprite *ProjectTreeModel::get<Sprite>(const QModelIndex &index);
+//template<> const Sprite *ProjectTreeModel::get<Sprite>(const QModelIndex &index) const;
+//template<> Sound *ProjectTreeModel::get<Sound>(const QModelIndex &index);
+//template<> const Sound *ProjectTreeModel::get<Sound>(const QModelIndex &index) const;
+//template<> Background *ProjectTreeModel::get<Background>(const QModelIndex &index);
+//template<> const Background *ProjectTreeModel::get<Background>(const QModelIndex &index) const;
+//template<> Path *ProjectTreeModel::get<Path>(const QModelIndex &index);
+//template<> const Path *ProjectTreeModel::get<Path>(const QModelIndex &index) const;
+//template<> Script *ProjectTreeModel::get<Script>(const QModelIndex &index);
+//template<> const Script *ProjectTreeModel::get<Script>(const QModelIndex &index) const;
+//template<> Font *ProjectTreeModel::get<Font>(const QModelIndex &index);
+//template<> const Font *ProjectTreeModel::get<Font>(const QModelIndex &index) const;
+//template<> TimeLine *ProjectTreeModel::get<TimeLine>(const QModelIndex &index);
+//template<> const TimeLine *ProjectTreeModel::get<TimeLine>(const QModelIndex &index) const;
+//template<> Object *ProjectTreeModel::get<Object>(const QModelIndex &index);
+//template<> const Object *ProjectTreeModel::get<Object>(const QModelIndex &index) const;
+//template<> Room *ProjectTreeModel::get<Room>(const QModelIndex &index);
+//template<> const Room *ProjectTreeModel::get<Room>(const QModelIndex &index) const;
+
+//template<> bool ProjectTreeModel::rename<Sprite>(const Sprite &sprite, const QString &newName);
+//template<> bool ProjectTreeModel::rename<Sound>(const Sound &sound, const QString &newName);
+//template<> bool ProjectTreeModel::rename<Background>(const Background &background, const QString &newName);
+//template<> bool ProjectTreeModel::rename<Path>(const Path &path, const QString &newName);
+//template<> bool ProjectTreeModel::rename<Script>(const Script &script, const QString &newName);
+//template<> bool ProjectTreeModel::rename<Font>(const Font &font, const QString &newName);
+//template<> bool ProjectTreeModel::rename<TimeLine>(const TimeLine &timeLine, const QString &newName);
+//template<> bool ProjectTreeModel::rename<Object>(const Object &object, const QString &newName);
+//template<> bool ProjectTreeModel::rename<Room>(const Room &room, const QString &newName);
diff --git a/resources.qrc b/resources.qrc
index cf8936e..4282990 100644
--- a/resources.qrc
+++ b/resources.qrc
@@ -63,5 +63,7 @@
         <file>icons/timeline.png</file>
         <file>icons/undo.png</file>
         <file>icons/object-file.png</file>
+        <file>icons/room-file.png</file>
+        <file>icons/timeline-file.png</file>
     </qresource>
 </RCC>