Surprise update! I dropped this for a while when one of the graphics libraries I use for it stopped working. But now I need a break from my other project, and I've learned a lot since last year, so it was a good time to finally get this update taken care of. Here it is, GeoTool Alpha 2.
I meant to just go straight to beta once all the new features were done, but there was a pretty terrible bug in Alpha 1 that I missed. I was enabling OpenGL3's 'forward compatibility mode', which made it incompatible with its own shaders. Not sure how it even worked at all for some of us. But I turned that off and also updated the shaders to GL3, so hopefully no more shader problems now (as long as you don't have a really old video card).
GeoTool can finally edit maps now, not just view them. An old GIF of terrain editing (I don't have video recording software on Windows, sorry):
Not everything is finished yet in this version, but it can edit and save SURF and HIGH maps. Let me know if you find more bugs -- there's probably plenty of them. I'll update the main post tomorrow(ish).