reopening the session management discussion...

[Brian J. Tarricone]

Hey guys,

A while ago, I suggested that perhaps xfwm4, xfdesktop, xfce4-panel,
etc. shouldn't use X11 session management to ensure startup, but just
use the fd.o autostart mechanism instead.  I believe I was shot down at
the time -- I think Olivier was opposed to the idea for some reason
that I can't remember.

However, I still see this as a good idea:

Pros:

* App can never "accidentally" fall out of the session due to a crash
(I guess I'm the biggest offender here). App will always be started when
the DE starts unless the user disables it.

* App can be programmatically removed from and added to the session by
deleting the .desktop file (or copying the systemwide file and adding
Hidden=true).  xfce4-session doesn't implement any method to do this.

Cons:

* Can't control startup order.  Only issue here is xfdesktop starting
before 'Thunar --daemon' on a system where dbus isn't set up properly.
All other apps can be started whenever, save xfsettingsd (which
xfce4-session explicitly starts).

Neutral:

* Can't respawn app if it crashes.  But xfce4-session
(intentionally) doesn't implement that part of the SM spec anyway.  If
we really want decent respawning, we should be using watchdog processes
anyway.  Ideally we just fix the bugs causing the crash, but that's not
always easy, and you can pretty much never verify that you've actually
fixed all crasher bugs.

So, what do people think?  I imagine there are some other cons I
haven't thought of, and maybe some pros as well.  If no one comes up
with convincing arguments against this idea, I'm definitely going to
remove libSM support from xfdesktop before 4.6.0.

	-brian