var newWindow = null;

function showImg(pic, w, h)
{
 if (newWindow != null)
 {
  if(!newWindow.closed)
  newWindow.close();
  newWindow = null;
 }
 w+=50;
 h+=110;
 newWindow = window.open('show_img.php?img='+pic,'edit','width='+w+',height='+h+',toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=yes,resizable=yes');
 newWindow.window.resizeTo(w,h);
 newWindow.focus();
}