var chat_win = null;
var w = 480, h = 340;
if (document.all) {
   w = document.body.clientWidth; 
   h = document.body.clientHeight;
}

if (document.layers) { 
	w = window.innerWidth; 
	h = window.innerHeight; 
}

function openBrWindow(theURL,winName,features) {
  chat_win=window.open(theURL,winName,features);
  if (chat_win.moveTo) {
  	chat_win.moveTo(w/2,h/2);
  }
}

function launch_chat(){
	if (chat_win && chat_win.open && !chat_win.closed){
		chat_win.focus();
	}else{
		openBrWindow('/bbcchat/intro.php?self=<?php echo $PHP_SELF;?>','chat','toolbar=no,scrollbars=no,scrollbars=0,width=550,height=350');
	}
}