QMainWindow::GroupedDragging not working without QMainWindow::AnimatedDocks

Open widgets\mainwindows\dockwidgets\

Change MainWindow::createDockWindows() to have:
setDockOptions(QMainWindow::AllowNestedDocks | QMainWindow::AllowTabbedDocks | QMainWindow::GroupedDragging);

Notice that we didn't specify AnimatedDocks

• Now it's impossible to get tabbed docks.
• Also, if you float two docks, and dock one into the other, it crashes.

See attached animated .gif