function wopen2(url,wname,flags,w,h) {
    var par='';
    var left = Math.floor( (screen.width - w) / 2);
    var top = Math.floor( (screen.height - h) / 2);
    if(flags&1)  { par+='scrollbars=1,';  } else { par+='scrollbars=0,';  }
    if(flags&2)  { par+='status=1,';      } else { par+='status=0,';      }
    if(flags&4)  { par+='resizable=1,';   } else { par+='resizable=0,';   }
    if(flags&8)  { par+='toolbar=1,';     } else { par+='toolbar=0,';     }
    if(flags&16) { par+='location=1,';    } else { par+='location=0,';    }
    if(flags&32) { par+='menubar=1,';     } else { par+='menubar=0,';     }
    if(flags&64) { par+='directories=1,'; } else { par+='directories=0,'; }
    //alert(par);
    win  = window.open(url,wname,'width=' + w + ', height=' + h + ',' + par + 'top=' + top + ',left=' + left);
    win.focus();
  }

function validate_form ( )
{
    valid = true;

    if ( document.shop_form.customer_email.value == "" )
    {
        alert ( "Fill in your email address please." );
        valid = false;
    }

    if ( document.shop_form.customer_name.value == "" )
    {
        alert ( "Fill in your name please." );
        valid = false;
    }

    if ( document.shop_form.code.value == "" )
    {
        alert ( "You must copy the code correctly." );
        valid = false;
    }

    return valid;
}