I have recently discovered a bug, when I drag & drop TreeCells in my TreeView.

Sometimes (like every 2nd/3rd try), I get the following exception when I try to start dragging a TreeCell:

java.lang.IllegalStateException: Cannot start drag and drop on node that is not in scene
at javafx.scene.Node.startDragAndDrop(Unknown Source)

It only appears, after I added a new node somewhere in the tree (or removed). So maybe it has something to do with reusing cells?

I am very afraid, that I can't isolate the problem into a small reproducable test case. (There it always worked).

I remembered, that that problem didn't occur in some beta build.

So I re-installed beta b14 and it worked.
After that I re-installed beta b19 and it didn't work.
So, somewhere between these versions, the error came in.

Jonathan, maybe you have an idea what it could be. Maybe you can remember any change you made to the tree view during Feb-Mar 2012 and give a hint!?