I just noticed; if I enter a search term, the menu instantly drops down to just above the panel. Erasing the entered text so search field is blank doesn't return the menu up on screen (to ~5.5cm above panel), but it stays low touching bottom panel.
So touching menu on panel bottom of my portrait display causes menu to open ~5.5cm above the panel with my prior display showing underneath menu. entering T & BACKSPACE (as if searching for terminal & then changing my mind) causes the MENU to re-draw touching the panel without the ~5.5cm gap.
