diff --git a/src/plugins/qmldesigner/components/propertyeditor/propertyeditorview.h b/src/plugins/qmldesigner/components/propertyeditor/propertyeditorview.h
index b9028aad3db..316164f4c29 100644
--- a/src/plugins/qmldesigner/components/propertyeditor/propertyeditorview.h
+++ b/src/plugins/qmldesigner/components/propertyeditor/propertyeditorview.h
@@ -44,6 +44,7 @@ class CollapseButton;
 class PropertyEditorWidget;
 class PropertyEditorView;
 class PropertyEditorQmlBackend;
+class ModelNode;
 
 class PropertyEditorView: public AbstractView
 {
@@ -66,8 +67,6 @@ public:
 
     void modelAboutToBeDetached(Model *model) override;
 
-    ModelState modelState() const;
-
     void variantPropertiesChanged(const QList<VariantProperty>& propertyList, PropertyChangeFlags propertyChange) override;
     void bindingPropertiesChanged(const QList<BindingProperty>& propertyList, PropertyChangeFlags propertyChange) override;
 
diff --git a/src/plugins/qmldesigner/components/stateseditor/stateseditorwidget.h b/src/plugins/qmldesigner/components/stateseditor/stateseditorwidget.h
index 231f4bfb431..8455ec63100 100644
--- a/src/plugins/qmldesigner/components/stateseditor/stateseditorwidget.h
+++ b/src/plugins/qmldesigner/components/stateseditor/stateseditorwidget.h
@@ -35,8 +35,6 @@ QT_END_NAMESPACE
 
 namespace QmlDesigner {
 
-class Model;
-class ModelState;
 class StatesEditorModel;
 class StatesEditorView;
 class NodeInstanceView;
diff --git a/src/plugins/qmldesigner/designercore/include/abstractproperty.h b/src/plugins/qmldesigner/designercore/include/abstractproperty.h
index b3e1c164130..65f3f666beb 100644
--- a/src/plugins/qmldesigner/designercore/include/abstractproperty.h
+++ b/src/plugins/qmldesigner/designercore/include/abstractproperty.h
@@ -108,6 +108,7 @@ protected:
     AbstractProperty(const PropertyName &propertyName, const Internal::InternalNodePointer &internalNode, Model* model, AbstractView *view);
     AbstractProperty(const Internal::InternalPropertyPointer &property, Model* model, AbstractView *view);
     Internal::InternalNodePointer internalNode() const;
+    Internal::ModelPrivate *privateModel() const;
 
 private:
     PropertyName m_propertyName;
diff --git a/src/plugins/qmldesigner/designercore/include/model.h b/src/plugins/qmldesigner/designercore/include/model.h
index b3a146b1746..d5f16be0ed4 100644
--- a/src/plugins/qmldesigner/designercore/include/model.h
+++ b/src/plugins/qmldesigner/designercore/include/model.h
@@ -40,7 +40,10 @@ QT_END_NAMESPACE
 
 namespace QmlDesigner {
 
-namespace Internal { class ModelPrivate; }
+namespace Internal {
+class ModelPrivate;
+class WriteLocker;
+} //Internal
 
 class AnchorLine;
 class ModelNode;
@@ -61,12 +64,10 @@ typedef QList<QPair<PropertyName, QVariant> > PropertyListType;
 class QMLDESIGNERCORE_EXPORT Model : public QObject
 {
     friend class QmlDesigner::ModelNode;
-    friend class QmlDesigner::NodeState;
-    friend class QmlDesigner::ModelState;
-    friend class QmlDesigner::NodeAnchors;
     friend class QmlDesigner::AbstractProperty;
     friend class QmlDesigner::AbstractView;
     friend class Internal::ModelPrivate;
+    friend class Internal::WriteLocker;
 
     Q_OBJECT
 
@@ -116,7 +117,7 @@ public:
 protected:
     Model();
 
-public:
+private:
     Internal::ModelPrivate *d;
 };
 
diff --git a/src/plugins/qmldesigner/designercore/model/abstractproperty.cpp b/src/plugins/qmldesigner/designercore/model/abstractproperty.cpp
index fa5595a4203..40a9d757766 100644
--- a/src/plugins/qmldesigner/designercore/model/abstractproperty.cpp
+++ b/src/plugins/qmldesigner/designercore/model/abstractproperty.cpp
@@ -106,6 +106,11 @@ Internal::InternalNodePointer AbstractProperty::internalNode() const
     return m_internalNode;
 }
 
+Internal::ModelPrivate *AbstractProperty::privateModel() const
+{
+    return m_model ? m_model->d : nullptr;
+}
+
 Model *AbstractProperty::model() const
 {
     return m_model.data();
diff --git a/src/plugins/qmldesigner/designercore/model/bindingproperty.cpp b/src/plugins/qmldesigner/designercore/model/bindingproperty.cpp
index 018075da663..dfea640fd57 100644
--- a/src/plugins/qmldesigner/designercore/model/bindingproperty.cpp
+++ b/src/plugins/qmldesigner/designercore/model/bindingproperty.cpp
@@ -84,9 +84,9 @@ void BindingProperty::setExpression(const QString &expression)
     }
 
     if (internalNode()->hasProperty(name()) && !internalNode()->property(name())->isBindingProperty())
-        model()->d->removeProperty(internalNode()->property(name()));
+        privateModel()->removeProperty(internalNode()->property(name()));
 
-    model()->d->setBindingProperty(internalNode(), name(), expression);
+    privateModel()->setBindingProperty(internalNode(), name(), expression);
 }
 
 QString BindingProperty::expression() const
@@ -239,9 +239,9 @@ void BindingProperty::setDynamicTypeNameAndExpression(const TypeName &typeName,
     }
 
     if (internalNode()->hasProperty(name()) && !internalNode()->property(name())->isBindingProperty())
-        model()->d->removeProperty(internalNode()->property(name()));
+        privateModel()->removeProperty(internalNode()->property(name()));
 
-     model()->d->setDynamicBindingProperty(internalNode(), name(), typeName, expression);
+     privateModel()->setDynamicBindingProperty(internalNode(), name(), typeName, expression);
 }
 
 QDebug operator<<(QDebug debug, const BindingProperty &property)
diff --git a/src/plugins/qmldesigner/designercore/model/internalnode_p.h b/src/plugins/qmldesigner/designercore/model/internalnode_p.h
index 9f70fe1e94f..0997c5a4ff4 100644
--- a/src/plugins/qmldesigner/designercore/model/internalnode_p.h
+++ b/src/plugins/qmldesigner/designercore/model/internalnode_p.h
@@ -40,8 +40,6 @@
 
 namespace QmlDesigner {
 
-class Model;
-
 namespace Internal {
 
 class InternalProperty;
diff --git a/src/plugins/qmldesigner/designercore/model/nodeabstractproperty.cpp b/src/plugins/qmldesigner/designercore/model/nodeabstractproperty.cpp
index 488988bbeb3..27b5a5c7469 100644
--- a/src/plugins/qmldesigner/designercore/model/nodeabstractproperty.cpp
+++ b/src/plugins/qmldesigner/designercore/model/nodeabstractproperty.cpp
@@ -86,18 +86,18 @@ void NodeAbstractProperty::reparentHere(const ModelNode &modelNode,  bool isNode
         throw InvalidReparentingException(__LINE__, __FUNCTION__, __FILE__);
 
     if (internalNode()->hasProperty(name()) && !internalNode()->property(name())->isNodeAbstractProperty())
-        model()->d->removeProperty(internalNode()->property(name()));
+        privateModel()->removeProperty(internalNode()->property(name()));
 
     if (modelNode.hasParentProperty()) {
         Internal::InternalNodeAbstractProperty::Pointer oldParentProperty = modelNode.internalNode()->parentProperty();
 
-        model()->d->reparentNode(internalNode(), name(), modelNode.internalNode(), isNodeList, dynamicTypeName);
+        privateModel()->reparentNode(internalNode(), name(), modelNode.internalNode(), isNodeList, dynamicTypeName);
 
         Q_ASSERT(!oldParentProperty.isNull());
 
 
     } else {
-        model()->d->reparentNode(internalNode(), name(), modelNode.internalNode(), isNodeList, dynamicTypeName);
+        privateModel()->reparentNode(internalNode(), name(), modelNode.internalNode(), isNodeList, dynamicTypeName);
     }
 }
 
diff --git a/src/plugins/qmldesigner/designercore/model/nodelistproperty.cpp b/src/plugins/qmldesigner/designercore/model/nodelistproperty.cpp
index 1d03c894181..d4735160c50 100644
--- a/src/plugins/qmldesigner/designercore/model/nodelistproperty.cpp
+++ b/src/plugins/qmldesigner/designercore/model/nodelistproperty.cpp
@@ -99,7 +99,7 @@ void NodeListProperty::slide(int from, int to) const
     if (to > count() - 1)
         throw InvalidPropertyException(__LINE__, __FUNCTION__, __FILE__, "<invalid node list sliding>");
 
-     model()->d->changeNodeOrder(internalNode(), name(), from, to);
+     privateModel()->changeNodeOrder(internalNode(), name(), from, to);
 }
 
 void NodeListProperty::reparentHere(const ModelNode &modelNode)
diff --git a/src/plugins/qmldesigner/designercore/model/nodeproperty.cpp b/src/plugins/qmldesigner/designercore/model/nodeproperty.cpp
index 6d9bcfd1de3..2d262c2ab63 100644
--- a/src/plugins/qmldesigner/designercore/model/nodeproperty.cpp
+++ b/src/plugins/qmldesigner/designercore/model/nodeproperty.cpp
@@ -59,9 +59,9 @@ void NodeProperty::setModelNode(const ModelNode &modelNode)
     }
 
     if (internalNode()->hasProperty(name()) && !internalNode()->property(name())->isNodeProperty())
-        model()->d->removeProperty(internalNode()->property(name()));
+        privateModel()->removeProperty(internalNode()->property(name()));
 
-    model()->d->reparentNode(internalNode(), name(), modelNode.internalNode(), false); //### we have to add a flag that this is not a list
+    privateModel()->reparentNode(internalNode(), name(), modelNode.internalNode(), false); //### we have to add a flag that this is not a list
 }
 
 ModelNode NodeProperty::modelNode() const
diff --git a/src/plugins/qmldesigner/designercore/model/signalhandlerproperty.cpp b/src/plugins/qmldesigner/designercore/model/signalhandlerproperty.cpp
index 21659a37e2f..3ad9280e7ad 100644
--- a/src/plugins/qmldesigner/designercore/model/signalhandlerproperty.cpp
+++ b/src/plugins/qmldesigner/designercore/model/signalhandlerproperty.cpp
@@ -71,9 +71,9 @@ void SignalHandlerProperty::setSource(const QString &source)
     }
 
     if (internalNode()->hasProperty(name()) && !internalNode()->property(name())->isSignalHandlerProperty())
-        model()->d->removeProperty(internalNode()->property(name()));
+        privateModel()->removeProperty(internalNode()->property(name()));
 
-    model()->d->setSignalHandlerProperty(internalNode(), name(), source);
+    privateModel()->setSignalHandlerProperty(internalNode(), name(), source);
 }
 
 QString SignalHandlerProperty::source() const
diff --git a/src/plugins/qmldesigner/designercore/model/variantproperty.cpp b/src/plugins/qmldesigner/designercore/model/variantproperty.cpp
index 259a6900ee2..dbdf1bb74e0 100644
--- a/src/plugins/qmldesigner/designercore/model/variantproperty.cpp
+++ b/src/plugins/qmldesigner/designercore/model/variantproperty.cpp
@@ -71,9 +71,9 @@ void VariantProperty::setValue(const QVariant &value)
     }
 
     if (internalNode()->hasProperty(name()) && !internalNode()->property(name())->isVariantProperty())
-        model()->d->removeProperty(internalNode()->property(name()));
+        privateModel()->removeProperty(internalNode()->property(name()));
 
-    model()->d->setVariantProperty(internalNode(), name(), value);
+    privateModel()->setVariantProperty(internalNode(), name(), value);
 }
 
 QVariant VariantProperty::value() const
@@ -120,9 +120,9 @@ void VariantProperty::setDynamicTypeNameAndValue(const TypeName &type, const QVa
     }
 
     if (internalNode()->hasProperty(name()) && !internalNode()->property(name())->isVariantProperty())
-        model()->d->removeProperty(internalNode()->property(name()));
+        privateModel()->removeProperty(internalNode()->property(name()));
 
-    model()->d->setDynamicVariantProperty(internalNode(), name(), type, value);
+   privateModel()->setDynamicVariantProperty(internalNode(), name(), type, value);
 }
 
 void VariantProperty::setDynamicTypeNameAndEnumeration(const TypeName &type, const EnumerationName &enumerationName)