REGRESSION: TreeView in Ensemble doesn't update properly on data change

To reproduce:
- Run Ensemble
- Click on All, Samples or Document button above the tree
RESULT:
- The tree is not updated properly:
- sometimes it gets updated when mouse cursor is moved over it
- sometimes new tree elements are drawn on top of old ones.

This is not reproducible with JavaFX 2.2

I also tried with -Dprism.dirtyopts=false but it didn't help.