function popup(urll,new_width,new_height) {
if (document.all){
var xMax = screen.width, yMax = screen.height;}
else
if (document.layers)
var xMax = window.outerWidth, yMax = window.outerHeight;
else 
var xMax = 800, yMax=600;
var xOffset = (xMax - new_width)/2, yOffset = (yMax - new_height)/2;
fen = open(urll,'fen','scrollbars=1,toolbar=0,menubar=0,resizable=0,width='+new_width+',height='+new_height+',screenX='+xOffset+',screenY='+yOffset+',top='+yOffset+',left='+xOffset+'');
fen.focus();
}