this is something that i am aware of for a long time now.. when the focus is on a window (like system settings or something different) and you rightclick on a free area on the plasma-desktop (or any widget) the context menu shows for half a second and then disappears .. (you'll have to click again) either don't show it (just change focus) or show it (change focus - raise context menu) .. but this looks like a bug to me.. reproducible: always
I cannot reproduce this issue. What's your focus policy? Click to focus, focus follows mouse or maybe focus under mouse?
I get a regular QMenu with this, which also grabs the pointer - even extreme focus stealing prevention and FSUM will not cause the described behavior - unless plasma is run "--nograb" (and as a result the popup will be closed because the desktop doesn't get or looses the focus for whatever reason)
waiting for answers to questions from comment #2
sorry.. i totally forgot about this bug.. this is not reproduceable anymore so i dare to say this is fixed ! :-) thx