Firefox fullscreen mouse event offsets

adding to the recent issues with firefox (version 140.13.0 currently)
I have experienced strange vertical offsets which vaguely remind me
of a similar firefox issue from way back which was briefly mentioned
in one of the other recent firefox threads.

namely in fullscreen windows (either pressing f11 or more commonly by
double clicking a video like youtube or an mp4-file dropped into
firefox to be played with the embedded player) there is a vertical
offset of the cursor position by what looks like exactly the height
of the titlebar.

the result is that the cursor has to be moved down by a few pixels to
click video controls (play/pause and position).

also if f11 is pressed to fullscreen the window the middle-click
autoscroll will be positioned a titlebar higher than the clicked
position and text selection will select text at a titlebars height
above where the cursor is.

this happens regardless of if 3dborders/3dtitles is turned on or not.

I think when this was raised way back there was a small fix for it,
but I have not investigated if this fix is relevant to the issue now.

hopefully the outlook web client wont completely destroy the formatting