To get it to work, I had to place the virtualgl libraries in
/etc/ld.so.preload before launching vmplayer.
Using vglrun failed with the dreaded
ERROR: ld.so: object 'lib??faker.so' from LD_PRELOAD cannot be preloaded: ignored.
I tried chmoding as per the virtualgl manual: 12: Using VirtualGL with setuid/setgid Executables, but that did not help.
I also tried launching vmplayer from a regular terminal with just:
DISPLAY=:THEXPRADISPLAY vglrun vmplayer
Same problem. Weird.
For now, I have added this information to wiki/Usage/OpenGL. It would be good to figure out what is going on here.
this ticket has been moved to: https://github.com/Xpra-org/xpra/issues/898