diff --git a/mobile/chrome/content/bindings.xml b/mobile/chrome/content/bindings.xml
index eb5ef3c1a74d..f8404041b4d2 100644
--- a/mobile/chrome/content/bindings.xml
+++ b/mobile/chrome/content/bindings.xml
@@ -1502,12 +1502,15 @@
       <method name="contentHasChanged">
         <body><![CDATA[
           let height = Math.floor(this.getBoundingClientRect().height);
+          let oldHeight = parseInt(this._spacer.getAttribute("height"));
           this.top = window.innerHeight - height;
           this._spacer.setAttribute("height", height);
 
-          let event = document.createEvent("Events");
-          event.initEvent("SizeChanged", true, false);
-          this.dispatchEvent(event);
+          if (height != oldHeight) {
+            let event = document.createEvent("Events");
+            event.initEvent("SizeChanged", true, false);
+            this.dispatchEvent(event);
+          }
         ]]></body>
       </method>
 
diff --git a/mobile/chrome/content/common-ui.js b/mobile/chrome/content/common-ui.js
index 2ee2ffaf7241..9af58e336c04 100644
--- a/mobile/chrome/content/common-ui.js
+++ b/mobile/chrome/content/common-ui.js
@@ -680,7 +680,7 @@ var FormHelperUI = {
           SelectHelperUI.resize();
           self._container.contentHasChanged();
 
-          self._zoom(this._currentElementRect, this._currentCaretRect);
+          self._zoom(self._currentElementRect, self._currentCaretRect);
         }, 0, this);
         break;
     }
