function show(href,name,mywidth,myheight){
  var posleft, postop;
  posleft=(screen.width-mywidth)/2;
  postop=(screen.height-myheight)/2;
   window.open(href,name,"resizable,scrollbars,width="+mywidth+",height="+myheight+",toolbar,location,menubar,status,left="+posleft+",top="+postop);
}