Oh, the site just describes some portability problems. WxPython is still under development and the Mac version is a little behind the Windows and Linux versions so some things just don't work in all OSes as expected. I just learned that Mac OSes have very strict rules concerning the menus: every app has to have a Help menu, only one frame can have a menubar, etc. It was also recommended to use the "official" id tags for menu items like "Open", "Save" and "About". So I just did that and uploaded a yet another new version. Dunno if it helps though...