Fix building the Mac version with GUI.
diff --git a/src/gui_mac.c b/src/gui_mac.c
index 2f0f7f8..d83a137 100644
--- a/src/gui_mac.c
+++ b/src/gui_mac.c
@@ -2597,6 +2597,12 @@
     return CallNextEventHandler(nextHandler, theEvent);
 }
 
+     void
+gui_mch_mousehide(int hide)
+{
+    /* TODO */
+}
+
 #if 0
 
 /*