function showOver(which) {
	var hide="nav" + which;
	var show="over_nav" + which;
	document.getElementById(hide).style.display = "none";
	document.getElementById(show).style.display = "block";
}

function hideOver(which) {
	var show="nav" + which;
	var hide="over_nav" + which;
	document.getElementById(hide).style.display = "none";
	document.getElementById(show).style.display = "block";
}