function popup_window(loc, w, h)
{
    var win;
    var opt;
    opt  = 'width=' +  w + ',height=' + h;
    // opt +=  ',top=' + 50 +   ',left=' + 50;
    opt += ',toolbar=0,status=0,location=0,menubar=0';
    opt += ',resizable=1,scrollbars=1';
    win = window.open(loc, "NRC_Archief", opt);

    win.focus();

    if (win.opener == null) win.opener = window;
}