When creating top-level menus with an ampersand shortcut, it seems Designer can dynamically re-assign its own shortcuts to avoid clashes.

However, this doesn't always work correctly. If a menu is added that clashes with one of Designer's dock widgets, the menu shortcut will be re-assigned, rather than the one on the dock widget.

For example, the Property Editor always has P as its ampersand shortcut. But if I create a menu called "&Play", it wil immediately get re-assigned to "Pla&y". Similarly, the Object Inspector always gets O, so a menu called "&Open" will get re-assigned to "Ope&n".

If the dock widgets are closed, the menu shortcut can be reset without the unwanted re-assignment taking place.