GEM has a window manager, of course

--HG--
branch : SDL-1.2
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/branches/SDL-1.2%402313

src/video/gem/SDL_gemvideo.c

@@ -467,6 +467,8 @@ int GEM_VideoInit(_THIS, SDL_PixelFormat *vformat)
 	SDL_AtariGL_InitPointers(this);
 #endif
 
+	video->info.wm_available = 1;
+
 	/* We're done! */
 	return(0);
 }