Quick controls with menus hijacking mouse clicks

Button or ToolButton controls associated with a Menu, when clicked
on cause future click events to be hijacked, so that subsequent clicks anywhere
else within the application window will cause the same menu to be opened/closed
again, without activating the controls currently under the mouse pointer. It's
only released by right-clicking or by clicking on the desktop or other
application. Reproduced with the WebEngine Quick Nano Browser example (with the
history and settings menus) and Qt Controls 1 Gallery example (with the Attach
button), with Qt 5.15.0 and 5.15.1, on macOS Catalina 10.15.5.