--- a/src/gtkvideo.h
+++ b/src/gtkvideo.h
@@ -120,6 +120,8 @@
   void gtk_video_unblank_screen (GtkVideo *);
 
   uint32_t gtk_video_get_capabilities (GtkVideo *); /* video port caps */
+
+  gboolean gtk_video_in_spu_button (GtkVideo *, int);
 #ifdef __cplusplus
 }
 #endif /* __cplusplus */