diff -r b7725d8f094d -r c25e7c9e26a0 client/js/renderer/scene.js
--- a/client/js/renderer/scene.js	Fri Sep 18 15:59:44 2015 +0200
+++ b/client/js/renderer/scene.js	Fri Sep 18 16:37:26 2015 +0200
@@ -74,7 +74,8 @@
         _originalScale = 1,
         _zooming = false,
         _lastTapX = 0,
-        _lastTapY = 0;
+        _lastTapY = 0,
+        _lastTap = 0;
 
         this.image_cache = {};
         this.icon_cache = {};