This looks nicely done. I tried an interface like this in a recent app. In my minds eye it was going to be an amazingly effective way to work with a hierarchy.

This looks nicely done. I tried an interface like this in a recent app. In my minds eye it was going to be an amazingly effective way to work with a hierarchy. In reality it sucked because it only works well with specific shapes of trees: shallow with many children at each node. In my case, I often had narrow trees with single child nodes, so it just became an inverted L wasting a huge amount of screen space: - - - - - -