Comment # 20 on bug 1100765 from Wolfgang Bauer

Ok, I tried on a Tumbleweed LiveCD now and can easily reproduce the problems.
It's clearly not related to the language.

So to summarize again:
Gimp apparently uses some kwin specific support code for screenshots if it
detects org.kde.KWin on the DBus session bus.

And this has two issues:

1) If compositing is turned off, taking a screenshot just gives an error
message "GDBus.Error:org.freedesktop.DBus.Error.UnknownObject: No such object
path '/Screenshot'"

The reason is that kwin's /Screenshot interface doesn't exist when compositing
is turned off.
Gimp should rather use the generic fallback code in that case.

2) The option "Select a region to grab" is missing.

Apparently that's not implemented/supported (yet?) in gimp's kwin support code.
It could also be done by using the fallback code I assume.
(that wouldn't work on Wayland though I think, maybe that's the reason for this
specific kwin support in the first place)

These are "regressions" in gimp 2.10, both work as expected with gimp 2.8 in
Leap 15.0 (maybe because it does use the fallback code and/or doesn't have
specific support for kwin yet).

Both are clearly problems in gimp though and need to be fixed there.
As gimp is not a KDE application, I'll reassign this.
Although I think it would be a good idea to report it upstream to the gimp
developers too.