Ok, tested the program quickly opening an existing map, and found this bug: in some entities the description label gets garbled text (both in the 3D view and in the selection panel, which suggests corrupted strings somewhere and not just a rendering problem).
In the image below, you see a bunch of regular path_corners with this problem:

This map has a lot of custom entities, but this seems unrelated to the bug, since most of non-standard entities show correclty their descriptive labels (at least in the 3D view):

Otherwise, I am really liking what I see, and my first impression of a quick and intuitive interface seems confirmed. A great contribution to the Quake community, SleepwalkR.