4.0.1 client connect to 4.0.1 server: transparent or black windows

[schvab]

When on Kubuntu 18.04 I get blank (transparent, only frame and title visible) or black windows when connecting 4.0.1 client to 4.0.1 server. Same behavior when connecting locally or via SSL from different PC (with same OS).
If client is 3.0.9 (on Kubuntu) or 4.0.1 on Win7 x64 all works OK.

[schvab]

output form bug report tool

[Antoine Martin]

That's odd, maybe it's the selection of renderer that's causing problems.
Can you try:

• toggling opengl on or off from the command line or system tray menu
• trying different types of windows, ie: xterm and firefox

Does this make any difference?
If it's opengl related, you may want to try --opengl=force.

[schvab]

when I run xpra attach ssl://schvab@schnuc.lan:14500/1 --ssl-server-verify-mode=none --speaker=enabled --microphone=disabled --min-quality=88 --opengl=force --title="@title@ schNUC"
the windows are see-through with only upper bar visible see 'Screenshot_20200520_080625.png'

when I switch off openGL (with openg=no and also in the tray menu) I get black windows see 'Screenshot_20200520_080512.png'

I try with firefox and xterm - in the 080625 its visible they behave the same.

[Antoine Martin]

From your screenshot, you seem to be connecting through a proxy server.
Have you tried connecting directly? (using a tunnel if needed)

Can you try connecting locally on the server and client? (with and without --mmap=off)

Does the problem go away if you use a different window manager? (metacity, fluxbox, or whatever)

[schvab]

I have new findings - the problem seems to be connected to the overall PC setup and openGL:

In the morning I had same behavior as seen on screenshots when connecting locally (on server, doing xpra attach :1) and when connecting over ssl with proxy from another PC but with same OS (kubuntu 18.04).
When I installed the 'another' PC to xubuntu 20.04 the remote ssl connection started working OK - windows were normal.
I updated the 18.04 server PC with all available updates but the behavior when connecting locally is still as seen on screenshots.
So when doing local connection (on server, doing xpra attach :1) also the mmap=off doesn't help and windows are still see-through.

It's probably worth to mention that both computers have Intel graphic accelerators.

I also tried today with third PC with kubuntu 18.04 and ati graphics as client and 4.0.1 worked fine.

P.S.: I get disconnected from ssl after random ~minutes, but that's different problem and I work around it by using ssh.