Created attachment 157026 [details]
Screenshot showing menu appearing distant from mouse

When using a virtual desktop of joined displays, LibreOffice incorrectly prevents drop-down menus from appearing in certain areas of the screen.

In particular, LibreOffice seems to use the smallest monitor to determine valid co-ordinates for menus, and constrains them to that area unnecessarily.

Example (see attached pic):

1. Create a virtual desktop with two monitors, where the smaller monitor is above the larger primary one, and they are right-aligned.

2. In LibreOffice Writer or Calc, click the "File" menu, which is near the top-left of the monitor.

3. Observe that the drop-down menu appears far over to the right, a long way from the mouse.

This makes it challenging to use the drop-down menus, as you must move the mouse quite a long way without accidentally passing over anything else that triggers a different drop-down menu.