Hi There, I have got an application that always crashes when having moved a dockwidget outside the mainwindow. When I leave the dockwidget at its iriginal Place on the left docking area the application will close fine.


App ist build up with this code (Control will instantiate and destroy mainwindow):

Qt Code: 
  1. int main(int argc, char *argv[])
  2. {
  3.     QApplication app(argc, argv);
  4.  
  5.     // app will destroy Control
  6.     // because it becomes Control's 
  7.     // parent object via constructur
  8.     Control::getSingleton(&app);
  9.     int ret = app.exec();
  10.  
  11.     return ret;
  12. } // app Object will be destroyed (and its children)
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IMHO the ~Control() Destructor will be called by the Application at last, so when finishing the application there will be (the destr. ist definitively called):

Qt Code: 
  1. /* singleton-private Constructor */
  2. Control::Control(QObject *parent) :
  3.     QObject(parent), 
  4. {
  5. ...
  6.     if(!mainWindow)
  7.         mainWindow = new MainWindow();
  8. ...
  9. }
  10.  
  11. Control::~Control()
  12. {
  13. ...
  14.     if(mainWindow) {
  15.         delete mainWindow; // will delete the ui including dockwidgets
  16.         mainWindow = NULL;
  17.     }
  18. }
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The Problem now is that when I have App destroying the mainwindow there comes a segmentation fault along - ending always in qwidget.cpp...

Qt Code: 
  1. ....
  2.   else if (!internalWinId() && isVisible()) {
  3.         qApp->d_func()->sendSyntheticEnterLeave(this);
  4. ....
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...where the d_func() with its scoped pointer will fail.

But: This only happens, when I have moved the DockWidet "Floating" away from its orignial Place in the main window. If I leave it there, everthing is ok.

As someone may see the stacktrace shows that the Dockwidget will make use of the qapplication d_func(). Am I wrong, or why do at least two parents try to delete the Widget (Mainwindow and App) ?

Qt Code: 
  1. 0	QScopedPointer<QObjectData, QScopedPointerDeleter<QObjectData> >::data	qscopedpointer.h	135	0x00ff01e6	
  2. 1	qGetPtrHelper<QScopedPointer<QObjectData, QScopedPointerDeleter<QObjectData> > >	qglobal.h	2314	0x008a63ff	
  3. 2	QApplication::d_func	qapplication.h	376	0x00eef9c4	
  4. 3	~QWidget	qwidget.cpp	1438	0x008ec5f8	
  5. 4	~QDockWidget	qdockwidget.cpp	1181	0x00c51fce	
  6. 5	QObjectPrivate::deleteChildren	qobject.cpp	1978	0x6a20f1b0	
  7. 6	~QWidget	qwidget.cpp	1476	0x008ec6dc	
  8. 7	~QMainWindow	qmainwindow.cpp	329	0x00c82888	
  9. 8	~MainWindow	mainwindow.cpp	50	0x004018c0	
  10. 9	~Control	control.cpp	83	0x00408feb	
  11. 10	QObjectPrivate::deleteChildren	qobject.cpp	1978	0x6a20f1b0	
  12. 11	~QObject	qobject.cpp	975	0x6a20d0f9	
  13. 12	~QCoreApplication	qcoreapplication.cpp	642	0x6a1fd127	
  14. 13	~QApplication	qapplication.cpp	1118	0x008aa05e	
  15. 14	qMain	main.cpp	14	0x00401400	
  16. 15	WinMain@16	qtmain_win.cpp	131	0x0040e612	
  17. 16	main		0	0x0040e338
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Any Comments ?