function viewFoto( url )
{
  var Maxbreedte = screen.width - 50;
  var Maxhoogte = screen.height - 100;
  Nieuwscherm = window.open(  url, 
                              "foto_up", 
                              "toolbar=no," +
                              "location=no," +
                              "scrollbars=no," +
                              "status=no," +
                              "menubar=no," +
                              "resizable=no," +
                              "width="+Maxbreedte+"px," +
                              "height="+Maxhoogte+"px");
  Nieuwscherm.focus();
}