function change_class(btnName) {
var menu = new Array('videos',
					 'photos',
					 'services',
					 'logistique',
					 'contact'
					 );

var i = 0;
var btn = document.getElementById(btnName);
var otherBtn;
while (i < menu.length)
{
	if (menu[i] == btnName)
		btn.className = "current";
	else if ((otherBtn = document.getElementById(menu[i])).className == "current")
		otherBtn.className = "normal";
	i++;
}
}