function winopen(url, id, w, h)
{
  w = w || 800;
  h = h || 700;
  t = (screen.height-h-30)/2;
  l = (screen.width-w-30)/2;
  window.open(url, 'win_'+id, "top="+t+",left="+l+",width="+w+",height="+h+",resizable=1,scrollbars=1");
}