Plane in Plugin

[Hans-Georg Menz <Hans-Georg Menz xampire de>]

Hello,

I am trying to create a plugin for F-Spot. Is it possible to add a plane 
(see <http://www.hansgeorgmenz.de/images/f-spot-extra-layer.png> for 
reference) to the UI of F-Spot or do I have to change the code of F-Spot 
for that?

Can someone please point me in the right direction, where I can find 
documentation on how to do this.

Greetings,
Hans-Georg