Floating toolbar that is wider than the mainwindow cannot be reattached into an empty dock

This is reproducible by modifying the "application" example and add all actions to the fileToolBar, leaving the editToolBar empty. When the example runs with the window as small as it can be made, undock the empty editToolBar and the fileToolBar. It is now impossible to redock either of them into the horizontal docks (the vertical still work). If the editToolBar is left in the dock, then the fileToolBar can be docked back without problems.