I have a number of Xwindow OpenGL programs using GLUT and Motif, on a MacBook,
and I had X11.App installed to start automatically. It always
produced a valid 'display' link, and the software ran fine.
A month ago, when I started one of these programs on my MacBook,
I got a pop up window that said "you have to replace X11 by XQuartz"
or something to that effect. I followed the link, installed XQuartz,
which deleted X11.App, and now even though XQuartz says it is running,
there are no links to a display, and I have never again been able
to run my software, which types out "no valid display."
I pay for Apple Developer privileges, called them, and they said, sorry
nothing we can do. Maybe you should contact XQuartz directly, as we
have nothing to do with X11 support any more. I have read every FAQ
and Mac blog I can find, and absolutely nothing of the many things I
have tried change my situation in the slightest: I still have no
'display' linked, and I still cannot run any of my OpenGL software.
I REALLY need this, and it must be something magic but easy, but I
cannot find it.
Please, Please, help?
In my case, I just installed XQuartz.
And, I double-clicked the icon of Xquartz, but it isn't run up.
my os is EL Capitan 10.11.6, and the version of XQuartz is 2.7.11.
Even error messages don't appear.
As mentioned in the release notes, the issue is a bug in Motif. I suggest you use the provided workaround or get Motif to fix their bugs.
A flat_namespace version of libXt is available in /opt/X11/lib/flat_namespace to help ease the transition (#96292)
Set DYLD_LIBRARY_PATH=/opt/X11/lib/flat_namespace when executing older non-compliant software (eg: Motif-based applications)
Motif users are encouraged to file bugs against Motif to encourage them to fix that library.
As for the GL issue, I suspect you're using Indirect GLX. X.org deprecated that quite some time ago, turning it off by default. As mentioned in the release notes, you can enable it with:
defaults write org.macosforge.xquartz.X11 enable_iglx -bool true