Eli Zaretskii wrote:
> Thanks.
> 
> I don't see anything strange here, the 1-pixel difference shouldn't
> have caused what you see.
> 
> Martin, any suggestions how to dig into this further?

What about implementing a global variable
'refresh-mode-line-after-scroll' which when set to 't' repaints the
mode-line after any scroll operation?  While it'd be just a workaround
treating the symptoms rather than the actual cause, it would be handy to
solve a whole class of problems, some potentially very hard to reproduce
and therefore fix, which would result in this same unwanted side effect
of corrupting the mode-line.  If the workaround is good enough, it can
possibly save Emacs developers time in the future, if the users are
happy sticking with it.  I'd be happy, BTW.

-- 
 ,= ,-_-. =.  Bruno Félix Rezende Ribeiro (oitofelix) [0x28D618AF]
((_/)o o(\_)) There is no system but GNU;
 `-'(. .)`-'  GNU Linux-Libre is one of its official kernels;
     \_/      All software must be free as in freedom;