patch for xfce4-session waiting for review

[Jérôme Guelfucci]

Hello,

Bug http://bugzilla.xfce.org/show_bug.cgi?id=1446 has a patch that has
been waiting for review for more than 2 years. I could not test this
patch against trunk because I've some build issues with plain trunk,
but I tested it against xfce4-session 4.4.2 and it works pretty fine.

If I understand correctly this patch is interesting because it removes
some duplicated code and makes the code lighter.

Thanks to the one that will find some time to review this,

Jérôme