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My guess is remote rendering via ssh uses a different set of drivers compared to rendering done sitting at the console of the CentOS8 machine.  Usually it is remote rendering that is broken more often than not because of differences in OpenGL drivers or the graphics card on the machine ssh’ing in receiving X11 forwarding, e.g. OpenGL trying to work in headless mode.

Either way, you can try setting  LIBGL_DEBUG=verbose to see what’s reported and/or different between the local and remote environments.
$ export LIBGL_DEBUG=verbose
… or just on the command line when you run the command …
$ LIBGL_DEBUG=verbose  freeview <arguments>

Graphics card drivers from vendors like NVIDIA can modify system libGL libraries and some people have found that for (remote) rendering to work those drivers need to be uninstalled.  I have not heard of that adversely affecting rending from the host machine’s console however.  But you might want to check you have the latest OpenGL drivers installed on the CentOS8 machine, e.g., MailScanner has detected a possible fraud attempt from "secure-web.cisco.com" claiming to be https://www.linuxquestions.org/questions/linux-software-2/how-can-i-check-if-i-have-installed-opengl-on-my-centos-server-4175583741/

This article is more geared towards remote debugging, but might give you some insight, https://www.scm.com/doc/Installation/Remote_GUI.html

- R.

On Mar 16, 2023, at 19:19, Wighton, Paul <PWIGHTON@mgh.harvard.edu> wrote:

Hi All,

I have a colleague who is trying to use FreeView on Red Hat Enterprise Linux 8, and there seems to be a transparency issue where windows behind the viewer are being displayed.  See attached screenshot.

This only happens when using FreeView on the desktop.  When using freeview over `ssh -X` everything looks good.

Any ideas, or debugging info we could pass along?

Thanks,

-Paul<Screen Shot 2023-03-16 at 4.17.47 PM.png>_______________________________________________
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