function popup( myLink, myW, myH, center)
{
var myC;
if( center) {
  if( screen.width) myC = (screen.width -myW)/2;
  if( myC <1) myC = 0;
  }
window.open( myLink ,'KerkoPopUp','status=yes,scrollbars=yes,resizable=no,menubar=no,toolbar=no,location=no,directories=no,width='+ myW +',height='+ myH +', top=0, left=' +myC);
}