diff --git a/lib/ace/mouse/mouse_handler.js b/lib/ace/mouse/mouse_handler.js
index cac4ce42..04e694e4 100644
--- a/lib/ace/mouse/mouse_handler.js
+++ b/lib/ace/mouse/mouse_handler.js
@@ -112,6 +112,12 @@ var MouseHandler = function(editor) {
 
         var self = this;
         var onMouseMove = function(e) {
+            if (!e) return;
+            // if editor is loaded inside iframe, and mouseup event is outside
+            // we won't recieve it, so we cancel on first mousemove without button
+            if (useragent.isWebKit && !e.which && self.releaseMouse)
+                return self.releaseMouse();
+
             self.x = e.clientX;
             self.y = e.clientY;
             mouseMoveHandler && mouseMoveHandler(e);
@@ -130,7 +136,7 @@ var MouseHandler = function(editor) {
             }
             self.isMousePressed = false;
             self.$onCaptureMouseMove = self.releaseMouse = null;
-            self.onMouseEvent("mouseup", e);
+            e && self.onMouseEvent("mouseup", e);
         };
 
         var onCaptureInterval = function() {