function open_popup(myurl,mywidth,myheight) {

	myleft = (screen.width - mywidth) / 2;

	mytop = (screen.height - myheight) / 2;

	work_popup = window.open(myurl, 'work_popup', 'width='+mywidth+',height='+myheight+',scrollbars=1,resizable=1,menubar=0,toolbar=0,status=0,location=0,directories=0,left='+myleft+',top='+mytop);

	work_popup.focus();

}