function openPopupWindow(url, width, height, scrolling, name) {
  if (!width) width = 350;
  if (!height) height = 350;
  if (!scrolling) scrolling = "no"; 
  if (!name) name = "win"+Math.round(Math.random()*1000); 
  
  features = "width="+width+","
           + "height="+height+","
           + "toolbar=no,"
           + "location=no,"
           + "status=no,"
           + "menubar=no,"
           + "scrollbars="+scrolling+","
           + "top="+(window.screen.height-height)/2+","
           + "left="+(window.screen.width-width)/2;
  window.open(url,name,features);
}