Backed out changeset 3edd47730527

MozReview-Commit-ID: AESEl0ht2Gi

browser/base/content/browser.js

@@ -8219,8 +8219,8 @@ var MousePosTracker = {
 
   handleEvent(event) {
     var fullZoom = this._windowUtils.fullZoom;
-    this._x = event.clientX / fullZoom;
-    this._y = event.clientY / fullZoom;
+    this._x = event.screenX / fullZoom - window.mozInnerScreenX;
+    this._y = event.screenY / fullZoom - window.mozInnerScreenY;
 
     this._listeners.forEach(function(listener) {
       try {