I have a legacy program (since 1992) on a dedicated remote machine as an X-client that while starting up tries to fix all kinds of oddities using
xmodmap and the like. Starting with 18.04 I note that many of these fixes no longer work.
How can (or should) the X-client detect that unity is running on the X-server? Or, to put it differently: What information does unity offer to X-clients beyond xdpyinfo and the like?
The connecting X-servers are more than 50 of various configurations (XQuartz, Ubuntu, Cygwin, and many Linuxes I never heard of before). They connect indirectly to the X-client otherwise known as a server.