Thanks for answering Ken,
dumping the stack is a good idea, I will do that next time I get my hands on jogl. But I'm still wondering why the idiom, you mentioned:
In general you should add your GLEventListener immediately after constructing the GLCanvas, before adding it to the component hierarchy.
is needed - are there any technical issues ?
If yes, these should be emphasized, because many awt and swing programmers probably are used to add/change/remove the needed event listeneres at any time.