This is a squash commit of the joint work from:
* Jan Tojnar (@jtojnar)
* Linus Heckemann (@lheckemann)
* Ryan Mulligan (@ryantm)
* romildo (@romildo)
* Tom Hunger (@teh)
- As noted on github, GDM needs different parameters for X.
- Making xserverArgs a true list instead of concat-string helps to
filter it and it feels more correct anyway.
- Tested: gdm+gnome, lightdm+gnome. There seems to be no logout option
in gnome, and gdm doesn't offer other sessions, but maybe these are normal.
This seems to have been confusing people, using both xlibs and xorg, etc.
- Avoided renaming local (and different) xlibs binding in gcc*.
- Fixed cases where both xorg and xlibs were used.
Hopefully everything still works as before.
Or else users may see this unfriendly message:
error: cannot coerce null to a string, at .../nixos/modules/services/x11/display-managers/gdm.nix:107:49