The default session setting in GDM is per user. Therefore, it is not of
much use to set it for the gdm user. (Nobody will log in as "gdm".)
Unfortunately, there seems to be no systemwide setting for the default
session, the AccountsService provides no such setting, and GDM just
hardcodes the fallback to use if it is not set in the AccountsService.
(GDM first tries "gnome", and if that is not available, it picks the
first session in the alphabet.)
Therefore, the best we can do right now is to set the default session
for the autoLoginUser. This is the case where it matters the most
anyway. We would also need the username of a non-autologin user in the
global storage to do any better.
Remove the hack that symlinks /usr/lib/lightdm/lightdm/gdmflexiserver as
/usr/bin/gdmflexiserver.
Upstream LightDM removed their gdmflexiserver implementation in 1.9.4 in
2013:
http://bazaar.launchpad.net/~lightdm-team/lightdm/trunk/revision/1841
In addition, LightDM was already adding the path containing its
gdmflexiserver implementation to PATH, so there was no use symlinking it
into /usr/bin, potentially overwriting the original version from GDM.
This must have been a workaround for an ancient LightDM version that
didn't even do that.
And finally, the hardcoded /usr/lib/lightdm/lightdm/gdmflexiserver path
was wrong on Fedora to begin with (we had used
/usr/libexec/lightdm/gdmflexiserver, but now the file is completely gone
because upstream removed it).
If a display manager is in the list, but not installed, do not return an
error message, but only print a debugging message and proceed.
This allows distributions that support multiple display managers to list
them all, independently of what the concrete live image will be using.
Do not use a YAML list when only a single entry actually works. (It was
just silently using the last one.)
Create the default_desktop_environment DesktopEnvironment tuple. Before,
the setting was silently ignored altogether.
This reverts commit 9c799b32e9.
This was already right before. default_desktop_environment.desktop_file is not a
variable, it's a field of a variable. This commit is not valid Python:
"SyntaxError: invalid syntax".
This also fixes some issues with the previous code:
* The code for LightDM only supported Xfce.
* The case where multiple desktop environments are installed was not
handled in a good way.
* We now also check that the xsession definition actually exists. This
allows handling the case where upstream changed the xsession
definition's name without renaming the invoked binary.
