We should define both USE_GUSI and USE_GUSI2.

Mac/mwerks/mwerks_tkplugin_config.h

@@ -2,8 +2,11 @@
 ** Special config-file for _tkinter plugin.
 */
 
-#define USE_GUSI1		/* Stdio implemented with GUSI */
-/* #define USE_GUSI2		/* Stdio implemented with GUSI */
+#define USE_GUSI2		/* Stdio implemented with GUSI 2 */
+/* #define USE_GUSI1	/* Stdio implemented with GUSI 1.X */
+#if defined(USE_GUSI1) || defined(USE_GUSI2)
+#define USE_GUSI
+#endif
 #define WITH_THREAD		/* Use thread support (needs GUSI 2, not GUSI 1) */
 #define USE_TK			/* Include _tkinter module in core Python */
 #define MAC_TCL			/* This *must* be on if USE_TK is on */