Just a very tiny suggestion, but having to hold ctrl to zoom feels quite strange for me, the UI looks and works a lot like the shader graph in unity, so my muscle memory is used to those interfaces where you can zoom with just the mousewheel (no modifier key). panning up and down is easily handled with scrollclick so i wouldn't need the scroll wheel up/down for that, i would rather the scroll wheel up/down zoom the window in and out since you have to do that frequently when navigating around a long tree. I will give more feedback as I use it more but it seems very well made so far!