function show_picture(strona, pic_w, pic_h, powrot){
  pic_l = (screen.width) ? (screen.width-pic_w)/2 : 0;
  pic_t = (screen.height) ? (screen.height-pic_h)/2 : 0;
  window.open('./popup.php?mact=3&fid='+strona+'&back='+powrot, 'new','menubar=no, toolbar=no, location=no, scrollbars=yes, resizable=no, status=no,width='+pic_w+', height='+pic_h+', left='+pic_l+', top='+pic_t).focus()
  return false;
}