fixes for panel mcs settings

[Jasper Huijsmans]

Hey all,

I just committed some changes to the way the panel handles the mcs
settings. This should the problems that were reported earlier, by
Olivier I believe (CVS HEAD only).

To make sure everything is right, you should log out of X (or kill
xfce-mcs-manager), remove ~/.xfce4/settings/panel.xml and log back in.

The settings dialog no longer depends on libxml, so that should fix some
problems benny reported.

It probably could do with some testing.

	Jasper

PS
It feels good to do some coding again.