Hi,
There seems to be a bug on the tree panel, where if you quickly double click, or keep clicking the <ext:Node>, it duplicates it's child nodes into the node?!
I've tested this on your examples page, and can replicate it there too if you quickly click the example section names. It doesn't do this in the 1.x examples, so is pointing to a 2.x bug. Just thought I'd point this out.
Cheers,
Kev