diff --git a/xpfe/global/resources/content/bindings/tabbox.xml b/xpfe/global/resources/content/bindings/tabbox.xml
index 6b3149bb4655..dd1076a9f975 100644
--- a/xpfe/global/resources/content/bindings/tabbox.xml
+++ b/xpfe/global/resources/content/bindings/tabbox.xml
@@ -144,15 +144,7 @@
       })]]>
       </field>
 
-      <field name="_eventNode">
-        var eventNode = this;
-        switch (this.getAttribute("eventnode")) {
-          case "parent": eventNode = this.parentNode; break;
-          case "window": eventNode = window; break;
-          case "document": eventNode = document; break;
-        }
-        eventNode;
-      </field>
+      <field name="_eventNode">this</field>
 
       <property name="eventNode" onget="return this._eventNode;">
         <setter>
@@ -168,6 +160,11 @@
       </property>
 
       <constructor>
+        switch (this.getAttribute("eventnode")) {
+          case "parent": this._eventNode = this.parentNode; break;
+          case "window": this._eventNode = window; break;
+          case "document": this._eventNode = document; break;
+        }
         this._eventNode.addEventListener("keypress", this._keyEventHandler, false);
       </constructor>