Then I see this.
Yeah, wxDesigner is a great software.

It's code was also totally broken with wx 2.9, and they didn't notice until I reported it.

2.2.x has a little
#ifndef wxGA_PROGRESSBAR
#define wxGA_PROGRESSBAR 0
#endif
that works around the bug. I'll forward-port it to trunk as soon (or as late...) as the file gets available for committing again.
If that's a problem for you I can also add the #define to any of the headers muuli includes, though it doesn't really belong there.