Hopefully the X servers have been fixed (in 5 years) :)

src/video/x11/SDL_x11modes.c

@@ -324,9 +324,11 @@ int X11_GetVideoModes(_THIS)
             fclose(metro_fp);
         }
     }
+#if 0 /* Let's try this again... hopefully X servers have improved... */
 #if defined(__alpha__) || defined(__sparc64__) || defined(__powerpc__)
     /* The alpha, sparc64 and PPC XFree86 servers are also buggy */
     buggy_X11 = 1;
+#endif
 #endif
     /* Enumerate the available fullscreen modes */
     if ( ! buggy_X11 ) {