[QDockWidget - Crash] Double Clicking to re-parent docks can cause a crash.

-Make sure all docks have: (AllowNestedDocks | AllowTabbedDocks | GroupedDragging)

-Add a few QDockWidgets to MainWindow
-Dock them all to them together
-Drag all docks out of the Main Window
-Double click their headers till they all snap to the top left of the screen
-Attempt to re-dock to main

-High reproduction rate but not 100% of the time.

-I also had it so my Docks aren't close able
-When I un-dock them and tab them together as they are floating, the close button appears (x at the top right in window)