Window buffers get stuck, random or periodic no redraws

[Tobiasz Karoń]

Hi!

I'm not sure if this is strictly an X11 problem, or maybe it's Kwin or
somethiing else. I already reported this to KDE developers.

I've recorded a video to explain the problem if you'd prefer that way (I
usually make videos about music production with FOSS on Linux):
https://youtu.be/yGLYmevwUus

I've recently noticed that a few programs are affected by a strange
problem: Ardour, LMMS, Firefox, Plasma Panel (KDE5).

Some windows of these programs will randomly stop redrawing, and will often
flicker like the display server is flipping between back and front buffers,
but not redrawing the windows as requested by the programs. The windows
will refresh if I resize or move them. Animations regarding changing
transparency by the window manager also trigger full redraw. If I gra a
windwow and slowly move it across my screen - it'll redraw for each frame
when it's location (or size) has changed since the last frame - as soon as
there's no change it'll stop redrawing at all.

The programs respond to keyboard input and mouse clicks (as demonstrated in
teh video) and work as usual - just the windoe redrawing is stuck.

I am running Linux Mint 18.2 with KDE5. This problem started a few weeks
ago on two remote machines (home studio and work) both running Linux Mint.
One uses an Nvidia GPU for display, but another uses Intel IGPU instead
(and uses Nvidia GPU only for CUDA computations). I have installled this
system on a laptop and I have not yet experienced that issue.

Another thing is some programs (Firefox, FreeCAD) will often stop redrawing
every couple of seconds for a few seconds. I'm writing this e-mail not in
my Firefox (as it's hunging up every few seconds, which makes it hard to
work with it) but in Kate instead.

I don't know if these problems are related.

Please let me know if there's anythingb I can do to help solve these
issues. If there are other places I should go to - please let me know. This
is a big itch for me.

-- 
- Tobiasz 'unfa' Karoń

http://soundcloud.com/unfa
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