Well, isn't the thing we need some sort of graphical development tool alá Delphi or Visual#?, in which you can chose to make it MUI/Zune/ReAction-compatible.
Otherwise I'm very pro the idea. Maybe trying to simplify the development with easy to use classes? I tried MUI and ReAction (no, sorry that's ClassAct) and actually didn't like either of them. I used Gadtools which was fairly simple (maybe because I had excellent tutorials) to use and understand.
I dont know if you mean doing a new .library (oh no, not another GUI-engine) or just something like opengui.h with functions. The latter option would be my bet, you could just compile the source and then link it with the appropriate openguiMUI/ReAct.o-file.
