I tracked it down somewhat:
if you change the value: "layout.css.devPixelsPerPx" in "about:config" to something else than "-1", "0" or "1" eg.: use "0.8" then you encounter the problem with misplaced menus this is reproduceable and really annoying.
I tracked it down somewhat:
if you change the value: css.devPixelsPe rPx"
"layout.
in "about:config"
to something else than "-1", "0" or "1"
eg.: use "0.8"
then you encounter the problem with misplaced menus
this is reproduceable and really annoying.