Custom File Browser - Example 4 problem on IE

window.opener.CKEDITOR.tools.callFunction( funcNum, fileUrl, function() {
  // Get the reference to a dialog window.
  var element, dialog = this.getDialog();
  // Check if this is the Image dialog window.
  if (dialog.getName() == 'image') {
    // Get the reference to a text field that holds the "alt" attribute.
    element = dialog.getContentElement( 'info', 'txtAlt' );
    // Assign the new value.
    if ( element )
      element.setValue( "alt text" );
  }
});