Yes, i broke my brain on it too but opengl only give us 255 object to pick and as scenes are made of more than 255 objects, it is useless badly till i won't know how to cast a ray in the scene but it's still a complex task for me and i can't loose the time needed to find it.
Anyhow, i tried to simplify the task anyway as much as i can and 3.1v that will be release soon will have alphabetically sorted object list and give a more clear appearance to tweak objects.
Hmm, crash after changing textures is strange as as you can see all Ricardo's track are working perfectly and they are all done with 3d Editor so i can only guess it comes from you...did you create any texture in the tool or just change one tex by another.
If you created new tex, you also have to create the tex file and add it to the given wad...