Fixed issue #597 - Crashes when the floating widget moves to the dock…

… manager and then tries to drag it back

src/DockContainerWidget.cpp

@@ -1643,6 +1643,15 @@ void CDockContainerWidget::removeDockArea(CDockAreaWidget* area)
 }
 
 
+//============================================================================
+QList<QPointer<CDockAreaWidget>> CDockContainerWidget::removeAllDockAreas()
+{
+	auto Result = d->DockAreas;
+	d->DockAreas.clear();
+	return Result;
+}
+
+
 //============================================================================
 CDockAreaWidget* CDockContainerWidget::dockAreaAt(const QPoint& GlobalPos) const
 {
@@ -1756,7 +1765,7 @@ void CDockContainerWidget::dropFloatingWidget(CFloatingDockContainer* FloatingWi
 	if (Dropped)
 	{ 
 		// Fix https://github.com/githubuser0xFFFF/Qt-Advanced-Docking-System/issues/351
-		FloatingWidget->hideAndDeleteLater();
+		FloatingWidget->finishDropOperation();
 
 		// If we dropped a floating widget with only one single dock widget, then we
 		// drop a top level widget that changes from floating to docked now

src/DockContainerWidget.h

@@ -139,6 +139,11 @@ class ADS_EXPORT CDockContainerWidget : public QFrame
 	 */
 	void removeDockArea(CDockAreaWidget* area);
 
+	/**
+	 * Remove all dock areas and returns the list of removed dock areas
+	 */
+	QList<QPointer<CDockAreaWidget>> removeAllDockAreas();
+
 	/**
 	 * Saves the state into the given stream
 	 */

src/FloatingDockContainer.cpp

@@ -776,7 +776,7 @@ CFloatingDockContainer::~CFloatingDockContainer()
 			continue;
 		}
 
-		// QPointer delete safety - just in case some dock wigdet in destruction
+		// QPointer delete safety - just in case some dock widget in destruction
 		// deletes another related/twin or child dock widget.
 		std::vector<QPointer<QWidget>> deleteWidgets;
 		for (auto widget : area->dockWidgets())
@@ -1167,14 +1167,19 @@ QList<CDockWidget*> CFloatingDockContainer::dockWidgets() const
 }
 
 //============================================================================
-void CFloatingDockContainer::hideAndDeleteLater()
+void CFloatingDockContainer::finishDropOperation()
 {
 	// Widget has been redocked, so it must be hidden right way (see 
 	// https://github.com/githubuser0xFFFF/Qt-Advanced-Docking-System/issues/351)
 	// but AutoHideChildren must be set to false because "this" still contains
 	// dock widgets that shall not be toggled hidden.
 	d->AutoHideChildren = false;
 	hide();
+	// The floating widget will be deleted now. Ensure, that the destructor
+	// of the floating widget does not delete any dock areas that have been
+	// moved to a new container - simply remove all dock areas before deleting
+	// the floating widget
+	d->DockContainer->removeAllDockAreas();
 	deleteLater();
 	if (d->DockManager)
 	{

src/FloatingDockContainer.h

@@ -258,9 +258,9 @@ private Q_SLOTS:
     QList<CDockWidget*> dockWidgets() const;
 
 	/**
-	 * This function hides the floating bar instantely and delete it later.
+	 * This function hides the floating widget instantly and delete it later.
 	 */
-	void hideAndDeleteLater();
+	void finishDropOperation();
 
 #if defined(Q_OS_UNIX) && !defined(Q_OS_MACOS)
     /**