/// <summary>
/// Closes the Umbraco dialog window if it is open
/// </summary>
/// <param name="returnVal">specify a value to return to add to the onCloseCallback method if one was specified in the OpenModalWindow method</param>
/// <returns></returns>
public ClientTools CloseModalWindow(string returnVal)
{
RegisterClientScript(Scripts.CloseModalWindow(returnVal));
return(this);
}