I like it! Here are some issues I found while testing it:
- GUI Settings dialog doesn't seem to work. In particular, setting the title and position BEFORE moving the window (so that the coordinates are blank).
- The top-level treeview entries have checkboxes next to them (Style, Constants, etc.)
- Settings dialog. But you probably already know that...
- Mode changing isn't usable for people without scroll wheels, such as those using laptops.
- Some small string things, like "LButton mode:move" (no space after colon) and the help dialog "GUI Creator Help,Help:".
Looks great so far.