HACK ALERT!
Make the CollectionTreeView correctly update itself on palette changes.

For some odd reason that has now eluded me for several hours, catching the change event and looking for palette changes yielded the _old_ palette, if it even bothered to catch the event at all...

This is a hackish workaround ( making MainWindow emit a signal with the new pallete on any changes ) but it works. Actually it might be worth connecting to this signal elsewhere as the method that is currently used in several places uses Qt3 support code.