Note that the children property also has to be an array collection.

Do you see any nodes at all, or just the top level nodes?

Have you tried calling TreeMenu.refreshTree() ? This function forces the tree to rebuild. Not the most elegant way, I admit.

Also, you could try to use (mxml) binding for the dataprovider, instead of setting it in AS. Note that when you do use binding, it generally only works for top-level nodes in the arraycollection, updates of children do not trigger binding, so you have to call myArraycollection.refresh();.

Hope this helps!

it seems as if the height problem occurs as soon as a branch is opened, closed and reopened.

But this is not my main problem. FlpTree is really great and looks and feels much better than the regular Flex Tree Component.
Unfortunately I can’t geht it to work as soon as the data comes from over AMF. AMF returns VO objects as array and I convert this to an array collection. This works with Flex Tree but not with FlpTree.
Inside my event handler I try to set the FlpTree dataProvider as ArrayCollection but nothing happens.

This is the code:
TreeMenu.dataProvider = new ArrayCollection(ArrayUtil.toArray(event.result));

Maybe anyone knows what I am doing wrong…