From 42f620daa2a1048c991594cae1885c81d5ba56ab Mon Sep 17 00:00:00 2001
From: Rachel Fenichel <fenichel@google.com>
Date: Tue, 21 Jun 2016 15:56:00 -0700
Subject: [PATCH] Check if matrix is null in mouseToSvg

---
 core/utils.js | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/core/utils.js b/core/utils.js
index 19ccc4cc8..89644fff9 100644
--- a/core/utils.js
+++ b/core/utils.js
@@ -315,6 +315,10 @@ Blockly.mouseToSvg = function(e, svg, matrix) {
   var svgPoint = svg.createSVGPoint();
   svgPoint.x = e.clientX;
   svgPoint.y = e.clientY;
+
+  if (!matrix) {
+    matrix = svg.getScreenCTM().inverse();
+  }
   return svgPoint.matrixTransform(matrix);
 };