1. Create QMainWindow with QToolbar only inside. Menu bar may be added too, it does not matter.
2. Drag the toolbar out of the window.
3. Resize the window to minimal possible size, so client area is not visible.
4. Drag the toolbar back to the window.
5. Normally, a toolbar moves back to client area, but in this case an application crashes.

Expected behaviour is resizing client area to approciate size for fitting a toolbar.

Stack trace:

0: abort
1: qt_message_fatal
2: QMessageLogger::fatal
3: qt_assert
4: QToolBarAreaLayout::item
5: QToolBarAreaLayout::plug
6: QMainWindowLayoutState::plug
7: QMainWindowLayout::plug
8: QToolBarPrivate::endDrag
9: QToolBarPrivate::mouseReleaseEvent
10: QToolBar::event
...