[X2Go-Dev] Bug#1391: X2Go Flickering on KDE remote desktop with compositor enabled

[Tom Butler]

Package: x2goserver

Version: 4.1.0.3

I am using X2Go to connect to a running KDE desktop over a gigabit LAN 
connection. Both the client machine (running x2goclient) and the server 
are running KDE Plasma 5.15. When the compositor is enabled, it causes 
flickering. It's most visible on windows with transparency effects like 
the taskbar and menu, however the window decorations of any window also 
flickers. I have uploaded a video of the problem here: 
https://www.youtube.com/watch?v=Hg8g1TXLndo  a rather unpleasant 
experience.

The server uses Intel graphics with an i7 8650u if it's a GPU/driver 
issue. The flickering does not happen on the server's display, only when 
viewed using x2go. The same thing happens in VNC, though it is 
significantly less frequent/annoying.

Ideally, x2go would support the compositor. Is it possible to just do 
full-screen polling? I can stream an x264 or vp9 video of the screen 
from the host and view the desktop that way but obviously that lacks 
input, although inefficient, it would solve any display issues if x2go 
could just stream a complete video from ffmpeg and then handle the input.

However, a workaround would be disabling the compositor on a connection. 
Is there currently any method that I can run a script on 
connect/disconnect or even just ask x2goserver how many clients are 
connected so I can stop the compositor when an x2go client connects and 
then re-enable it when there are no clients?