function openwindow(url,w,h)
  {
   
    var winwidth = screen.availWidth;
    var winheight = screen.availHeight;
    var leftt=Math.floor((winwidth/2)-(w/2));
    var topt=Math.floor((winheight/2)-(h/2));
    window.open(url,'','left='+leftt+',top='+topt+',width='+w+', height='+h+', toolbar=0, location=0, directories=0,status=1, menubar=0, resizable=1, scrollbars=yes')
  };