--- a/toolkit/content/widgets/scrollbox.xml
+++ b/toolkit/content/widgets/scrollbox.xml
@@ -409,25 +409,18 @@
             // In the RTL case, this means the _first_ element in the
             // scrollbox is visible
             if (this._isRTLScrollbox)
               disableUpButton = true;
             else
               disableDownButton = true;
           }
 
-          if (this._scrollButtonUp.disabled != disableUpButton ||
-              this._scrollButtonDown.disabled != disableDownButton) {
-            this._scrollButtonUp.disabled = disableUpButton;
-            this._scrollButtonDown.disabled = disableDownButton;
-
-            var event = document.createEvent("Events");
-            event.initEvent("UpdatedScrollButtonsDisabledState", true, false);
-            this.dispatchEvent(event);
-          }
+          this._scrollButtonUp.disabled = disableUpButton;
+          this._scrollButtonDown.disabled = disableDownButton;
         ]]></body>
       </method>
     </implementation>
 
     <handlers>
       <handler event="DOMMouseScroll"><![CDATA[
         // prevent horizontal scrolling from scrolling a vertical scrollbox
         if (event.axis == event.HORIZONTAL_AXIS &&