This is a list of preprocessor symbols used in the wxWindows source.

GUIs:
-----

__X__           any X, but not GTK
__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.
__WIN32__       WIN32 API
__NT__          Windows NT
__WXCURSES__    CURSES
__WXSTUBS__     Stubbed version ('template' wxWin implementation)

In fact, they should better all start with __WX instead of __ only. 
The only GUIs implemented for 2.0 are __WXGTK__, __WXMSW__ and __WXMOTIF__
yet. Any new ones, please start the define with __WX.

OSes/machines:

__HPUX__
__SVR4__
__SYSV__
__LINUX__
__SGI__
__ULTRIX__
__BSD__
__VMS__
__SUN__         Any Sun
__SUNOS__
__SOLARIS__
__ALPHA__
__AIX__
__DATA_GENERAL__
__OSF__
__FREEBSD__

Compilers:
----------

__GNUWIN32__    Gnu-Win32 compiler
__DJGPP__       DJGPP
__GNUG__        Gnu C++ on any platform
__BORLANDC__    Borland C++
__WATCOMC__     Watcom C++
__SYMANTECC__   Symantec C++
__VISUALC__     VC++
__SUNCC__       Sun CC
__XLC__         ?? compiler

wxWindows modes:
----------------

__WXDEBUG__       usage: #ifdef __WXDEBUG__ (=> debug mode, else => release)
WXDEBUG         usage: #if DEBUG (0: release, 1: minimal debug code, ...)