I can now save the worlds and load them back, mostly in the format that the game reads. However the editor has grown much more powerful than the game and many things the editor has aren't supported yet.
Objects can rotate and move from one place to another; most can be scripted on some events, and I've also added the ability to read keyframe animations from the texture and the editor will animate those as well.
These images show a couple of test levels that were just read back from file. I also moved the add-object palette up to the toolbar.