how to report bug against xorg-server?

[Richard Cobbe]

What's the best way to report a bug against xorg-server?  I'm happy to open
a ticket on the MacPorts trac instance, but this is more an application
problem than a compilation or installation issue, and the ticket guidelines
at <https://guide.macports.org/#project.tickets> suggest that application
errors should be reported to the upstream developers -- and I've lost track
of who that is at this point.  This is clearly a MacOS issue, so I very
much doubt that reporting it to x.org is appropriate.

(The specific bug: the dialog box that appears when I choose "Customize..."
from the Applications menu does not handle Mojave's dark mode well at all;
it's borderline unusable.)

Thanks,

Richard