function checkPressedKey(e){
	var unicode;
	if( !e ) {
	  //if the browser did not pass the event information to the
	  //function, we will have to obtain it from the event register
	  if( window.event ) {
		//Internet Explorer
		e = window.event;
	  } else {
		//total failure, we have no way of referencing the event
		return;
	  }
	}
	if( typeof( e.keyCode ) == 'number'  ) {
	  //DOM
	  e = e.keyCode;
	} else if( typeof( e.which ) == 'number' ) {
	  //NS 4 compatible
	  e = e.which;
	} else if( typeof( e.charCode ) == 'number'  ) {
	  //also NS 6+, Mozilla 0.9+
	  e = e.charCode;
	} else {
	  //total failure, we have no way of obtaining the key code
	  return;
	}

	if ( e == 27 )
	{
		tb_remove();
	}
}

document.onkeyup = checkPressedKey;