#include <gtk/gtk.h>
/* Platform dependant OpenGL includes */
-#ifdef USE_MAC
+#ifdef SYS_MAC
#include <OpenGL/gl.h>
#include <OpenGL/glu.h>
#else
#include <GL/gl.h>
#include <GL/glu.h>
+#include <GL/glext.h>
#endif
/* Call before widget is realized */