var target = "self" //Destination des URL: "blank", "top" "self" ou "nom du cadre" 

function envoie(frm){
URL = frm.menu.options[frm.menu.selectedIndex].value
if (frm.menu.selectedIndex != 0)
	{if (target == "blank") mywindow = window.open(''+URL+'');
	else if (target == "self") document.location = URL;
		else parent.frames[target].location  = URL; 
	}
else alert('Veuillez faire un choix au menu.');
}