Fix feedkeys in timer callback

Author: ichizok

src/MacVim/gui_macvim.m

@@ -407,9 +407,19 @@
     [[MMBackend sharedInstance] flushQueue:YES];
 
 #ifdef MESSAGE_QUEUE
+# ifdef FEAT_TIMERS
+    did_add_timer = FALSE;
+# endif
     parse_queued_messages();
+# ifdef FEAT_TIMERS
+    if (did_add_timer)
+        return FAIL;
+# endif
 #endif
 
+    if (input_available())
+        return OK;
+
     return [[MMBackend sharedInstance] waitForInput:wtime];
 }