[Gimp-user] GUI font unreadable/missing/missing glyphs?

[Stefan Schwarzer <stefan schwarzer gmx net>]

Hi everybody,

I am occasionally using gimp on debian testing, Thinkpad 460p, 64bit, KDE desktop. My installation has aged 
for a while
and contains smaller contributions from the unstable and stable archive as well. gimp is at version 2.10.18

Problem is, gimps GUI interface font stopped to be readable or to be present on my system at some point and 
instead on all menues I see
what I understand as replacements for missing font glyphs (i.e. small rectangles with 4 numbers/letters that 
represent the
character encoding, see attached screenshot). I have removed and re-installed the program (the packages gimp, 
gimp-data) in the hope that some
dependency (the interface font) would be pulled in in the progress. I have checked the general font 
configuration (fontconfig is
installed, package version 2.13.1). When I start gimp from a terminal, there are no error messages.
In .xsession-errors, looking for gimp, I find

couldn't find ("nautilus.desktop") which is supposedly extended by "nautilus-sendto"
couldn't find ("gimp.desktop") which is supposedly extended by "gimp-data-extras"

which may or not be relevant, though I do not understand that message.

Which font is required to be installed or what is the process by which gimp selects
the interface font? Has anybody seen and solved this problem?

Thanks a lot,

Stefan