__WXMOTIF__ Motif
__WXXT__ Xt; mutually exclusive with WX_MOTIF (?)
__WXGTK__ GTK
+__WXGTK12__ GTK 1.2 or higher
__WXMSW__ Any Windows
+__WXWINE__ WINE (i.e. Win32 on Unix)
__WXMAC__ MacOS
+__WXPM__ OS/2 native Presentation Manager
__UNIX__ any Unix
__WINDOWS__ any Windows
__WIN95__ GUI for Windows 95 and above; NT 4.0 and above.