-void (*MR_Keydown) (int key, char ascii);
-void (*MR_Draw) (void);
-void (*MR_ToggleMenu_f) (void);
-void (*MR_Shutdown) (void);
+extern void (*MR_Keydown) (int key, char ascii);
+extern void (*MR_Draw) (void);
+extern void (*MR_ToggleMenu_f) (void);
+extern void (*MR_Shutdown) (void);