function validate_form(thisform) {
  with (thisform) {
    if (document.formmail.realname.value==null || document.formmail.realname.value=="") { alert("Please enter your name."); document.formmail.realname.focus(); return false; }

    if (document.formmail.email.value==null || document.formmail.email.value=="") { alert("Please enter your E-mail address."); document.formmail.email.focus(); return false; }

    if (document.formmail.phone.value==null || document.formmail.phone.value=="") { alert("Please enter your phone number."); document.formmail.phone.focus(); return false; }

    if (document.formmail.quantity.value==null || document.formmail.quantity.value=="") { alert("Please enter the quantity of shirts you want."); document.formmail.quantity.focus(); return false; }

    if (isNaN(document.formmail.quantity.value)) { alert("Please enter a numeric value of shirts."); document.formmail.quantity.focus(); return false; }

    if (document.getElementById('ColorFront').options[0].selected && document.getElementById('ColorBack').options[0].selected) { alert("Please select at least one color."); return false; }

    var printing_choice=false;
    for (i=0; i<document.formmail.printing.length; i++) if (document.formmail.printing[i].checked) printing_choice=true;
    if (!printing_choice) { alert("Please select a printing type."); return false; }

    var art_choice=false;
    for (i=0; i<document.formmail.art.length; i++) if (document.formmail.art[i].checked) art_choice=true;
    if (!art_choice) { alert("Please select an art source."); return false; }
  }
}