At the end of the last week I actually managed to remove ALL Microsoft MFC bindings from CaWE.
It's entirely http://www.wxWidgets.org based now, with only a single source code file left referring to the Win32 API directly. (This is not a problem for porting to Linux, though.)
What remains is
- to fix several loose ends that were introduced during the port, i.e. re-add missing features, and fixing bugs, and
- to add more Ca3DE-specific features.