Here’s my crappy attempt at getting the latest version in vache’s repository (2 years old) to work:
I don’t know how much changed since then, but the newer version seems to have some initial work on overmap support (it doesn’t seem to be working), support for rubble and similar extras and seems to be less slow than the version in OP.
I’m not sure if I bundled all the necessary libraries in my release.
I don’t understand Qt (the graphics library used) well, but I might be able to get the editor back into tolerable shape.