function addEvent( obj, type, fn ) {
  if ( obj.attachEvent ) {
    obj["e"+type+fn] = fn;
    obj[type+fn] = function() { obj["e"+type+fn]( window.event ); }
    obj.attachEvent( "on"+type, obj[type+fn] );
  } else
    obj.addEventListener( type, fn, false );
  }
function removeEvent( obj, type, fn ) {
  if ( obj.detachEvent ) {
    obj.detachEvent( "on"+type, obj[type+fn] );
		obj[type+fn] = null;
  } else
    obj.removeEventListener( type, fn, false );
}