[Banshee-List] Changes to drag 'n' drop

[LCID Fire <lcid-fire gmx net>]

Hi.
I'm currently trying to write a new plugin for banshee but I'm stuck
because of some limitations in the tree.
Appearently I cannot drop any Playlist on my new written Source. It
seems like most of the 'may drop' code is hardcoded. So my question: is
somebody already working on getting this system more flexible - or
should I do it?

Also I'd like to have the option to select multiple Sources in the tree.
I think currently it just handles single select.

Also it would be a real help if you'd rely more one interfaces than base
classes - because this also makes some problem on attemts to implement
wrapper classes.