function odpri_okno(url, width, height)
{
  var scrnwdth = 0;
  var scrnhght = 0;
  var wdth = width;
  var hght = height;
  var lft;
  var tp;
  if((window.screen) && (screen.width) && (screen.height)) {scrnwdth = screen.width; scrnhght = screen.height;}
  if(scrnwdth != 0) lft = (scrnwdth - wdth)/2;
  if(scrnhght != 0) tp = (scrnhght - hght)/2;
  var openwnd = null;
  openwnd = window.open(url, 'openwnd', 'width=' + wdth + ',height=' + hght + ',left=' + lft + ',top=' + tp + ',screenX=' + lft + ',screenY=' + tp + ',menubar=no,toolbar=no,location=no,directories=no,status=no,scrollbars=no,resizable=no');
  if (openwnd.blur) openwnd.focus();
}