As explained so many times in the forum, what you see as "the GSX Menu", is NOT a GSX menu. It's the standard Simconnect menu, which is shared by all applications that use a similar menu. This means:
- GSX doesn't try to do ANY handling of the keyboard while you are in the menu.
- No other application that uses the standard Simconnect menu will do any keyboard handling either.
GSX ( or any other application that use the Simconnect menu ), doesn't know, doesn't try and doesn't care if you use the keyboard or the mouse to select an entry. While the menu is displayed, the handling is done *entirely* by the simulator, which will return to GSX ( or any other application that use the Simconnect menu ) which choice you made, WITHOUT telling the app ( GSX or any other similar app ) if the choice was made with the keyboard or the mouse. If LM would add a new input method in the future, like VR controllers, or voice input or anything else that could be used to select an entry in the menu, GSX ( and any other app ), will NOT KNOW if you used alternative methods, and won't have any control over it.
From your report the mouse selection works while the keyboard doesn't, looks like the problem is the simulator window not being on focus, so it won't process the keyboard, but this won't happen with the mouse, because the moment you click on the menu, you ALSO put the simulator window in focus.