Welcome: Derive Core::Button from QAbstractButton

Enable a hover effect on macOS and remove the need for the setFlat hack.

Change-Id: Iea77ccaddcff0e9ad9299ffda8584160dca6413a
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Marcus Tillmanns <marcus.tillmanns@qt.io>

src/plugins/coreplugin/welcomepagehelper.cpp

@@ -134,12 +134,10 @@ static const TextFormat &buttonTF(Button::Role role, WidgetState state)
 }
 
 Button::Button(const QString &text, Role role, QWidget *parent)
-    : QPushButton(text, parent)
+    : QAbstractButton(parent)
     , m_role(role)
 {
-    // Prevent QMacStyle::subElementRect(SE_PushButtonLayoutItem) from changing our geometry
+    setText(text);
-    setFlat(true);
-
     updateMargins();
     if (m_role == SmallList)
         setCheckable(true);

src/plugins/coreplugin/welcomepagehelper.h

@@ -70,7 +70,7 @@ CORE_EXPORT QWidget *createRule(Qt::Orientation orientation, QWidget *parent = n
 
 } // namespace WelcomePageHelpers
 
-class CORE_EXPORT Button : public QPushButton
+class CORE_EXPORT Button : public QAbstractButton
 {
 public:
     enum Role {

src/plugins/extensionmanager/extensionsbrowser.h

@@ -9,10 +9,10 @@
 #include <QWidget>
 
 QT_BEGIN_NAMESPACE
+class QAbstractButton;
 class QItemSelectionModel;
 class QLineEdit;
 class QListView;
-class QPushButton;
 class QSortFilterProxyModel;
 QT_END_NAMESPACE
 
@@ -58,7 +58,7 @@ private:
 
     QScopedPointer<QStandardItemModel> m_model;
     QLineEdit *m_searchBox;
-    QPushButton *m_updateButton;
+    QAbstractButton *m_updateButton;
     QListView *m_extensionsView;
     QItemSelectionModel *m_selectionModel = nullptr;
     QSortFilterProxyModel *m_filterProxyModel;

src/plugins/welcome/welcomeplugin.cpp

@@ -73,7 +73,7 @@ private:
     TopArea *m_topArea;
     SideArea *m_sideArea;
     QList<IWelcomePage *> m_pluginList;
-    QList<QPushButton *> m_pageButtons;
+    QList<QAbstractButton *> m_pageButtons;
     QButtonGroup *m_buttonGroup;
     Id m_activePage;
     Id m_defaultPage;