diff --git a/embedding/components/ui/progressDlg/nsIProgressDialog.idl b/embedding/components/ui/progressDlg/nsIProgressDialog.idl
index 9c4f80206761..f1bc69808ec0 100644
--- a/embedding/components/ui/progressDlg/nsIProgressDialog.idl
+++ b/embedding/components/ui/progressDlg/nsIProgressDialog.idl
@@ -47,9 +47,6 @@ interface nsIObserver;
  *      the dialog itself, so it won't get freed until the dialog closes.
  *      The dialog will keep the instance alive, so typically one does
  *      not need to hold a reference to it.
- *
- * Important Note: Implementors of this interface must also implement
- *                 nsISupportsWeakReference.
  */
 
 [scriptable, uuid(88A478B3-AF65-440a-94DC-ED9B154D2990)]
diff --git a/embedding/components/ui/progressDlg/nsProgressDialog.js b/embedding/components/ui/progressDlg/nsProgressDialog.js
index 1680606b4c3d..4a6eae6dad80 100644
--- a/embedding/components/ui/progressDlg/nsProgressDialog.js
+++ b/embedding/components/ui/progressDlg/nsProgressDialog.js
@@ -293,7 +293,6 @@ this.dump( "nsProgressDialog::onStatusChange, status=" + this.hex( aStatus ) + "
     QueryInterface: function (iid) {
         if (!iid.equals(Components.interfaces.nsIProgressDialog) &&
             !iid.equals(Components.interfaces.nsIWebProgressListener) &&
-            !iid.equals(Components.interfaces.nsISupportsWeakReference) &&
             !iid.equals(Components.interfaces.nsIObserver) &&
             !iid.equals(Components.interfaces.nsISupports)) {
             throw Components.results.NS_ERROR_NO_INTERFACE;
@@ -452,8 +451,8 @@ this.dump( "nsProgressDialog::onStatusChange, status=" + this.hex( aStatus ) + "
         var title = this.saving ? this.getString( "savingTitle" ) : this.getString( "openingTitle" );
 
         // Use file name as insert 1.
-        var fname = this.target.unicodePath;
-        var n = this.target.unicodePath.lastIndexOf( "\\" );
+        var fname = this.target? this.target.unicodePath : " ";
+        var n = fname.lastIndexOf( "\\" );
         title = this.replaceInsert( title, 1, fname.substring( n + 1 ) );
 
         // Use percentage as insert 2.