add the standard close button to the Add window

macosx/AddWindowController.m

@@ -190,6 +190,12 @@
 }
 
 - (void) cancelAdd: (id) sender
+{
+    [[self window] performClose: sender];
+}
+
+//only called on cancel
+- (BOOL) windowShouldClose: (id) window
 {
     [fTimer invalidate];
     fTimer = nil;