Hello Osama Nasr,
> By the way, I've installed GIMP, although there was a bug
> (libmypaint-common #906144).
> I don't know if that have a relation or not.
On a short look I guess this is not related.
> konqueror: ../nouveau/pushbuf.c:723: nouveau_pushbuf_data: Assertion `kref' failed.
> Received signal 6
> #0 0x7f73c396cbde <unknown>
> #1 0x7f73c396ccf0 <unknown>
> #2 0x7f73c396d327 <unknown>
> #3 0x7f73f7a1f940 <unknown>
> #4 0x7f73f7a1f8bb gsignal
> #5 0x7f73f7a0a535 abort
> #6 0x7f73f7a0a40f <unknown>
> #7 0x7f73f7a180f2 __assert_fail
> #8 0x7f73ee7a059f nouveau_pushbuf_data
> #9 0x7f73ee7a0503 nouveau_pushbuf_data
> #10 0x7f73ee7a062f <unknown>
> #11 0x7f73ee7a0a7f <unknown>
> #12 0x7f73ee7a1670 nouveau_pushbuf_kick
> #13 0x7f73ed89dbc6 <unknown>
> #14 0x7f73ed9c5faf <unknown>
> #15 0x7f73ed5a0b37 <unknown>
> #16 0x7f73ee77b243 <unknown>
> #17 0x7f73effa8146 <unknown>
> #18 0x7f73f60b6c4b QOpenGLContext::swapBuffers()
> ...
I guess this is the most interesting part and points to
an error in the nouveau driver.
This bug might be related:
https://bugs.freedesktop.org/show_bug.cgi?id=91632
It may help if you also add the output of this command, if installed:
glxinfo -B
Kind regards,
Bernhard