QMainWindow::restoreDockWidget() doesn't restore correctly when GroupedDragging is set

When saving the main window state and restoring it, the floating and grouped dock widgets are not restored correctly. The restored state is usually the state when you grouped the windows. If you move or resize the grouped window, it seems that the state is not stored.

The attached modified Qt Dock Widgets Example demonstrates the problem. Float and group the dock widgets and move/resize them. Then restart the app.