var chatwin = null;
function chat(params, chatwin)
{
// activate existing window if exists and not closed
if (chatwin != null && !chatwin.closed) {
chatwin.focus();
return chatwin;
}
var url = 'http://clavardage.sematix.com:8000/web/chat_hall';
var name = 'chat';
var width = 600;
var height = 500;
var pos_y = Math.round((screen.availHeight - height)/2);
var pos_x = Math.round((screen.availWidth - width)/2);
var new_window = window.open('', name, 'menubar=no, status=no, scrollbars=no, resizable=no, width=' + width + ', height=' + height + ', top=' + pos_y + ', left=' + pos_x);
if (!new_window) return false;
var html = '';
html += '';
html += '';
html += '