function menu_over(i) {set_visible("submenu_" + i, true);}
function menu_out(i) {set_visible("submenu_" + i, false);}
function set_visible(id, v) {
	if(document.all) return document.all[id].style.visibility = v?'visible':'hidden';
	if(document.getElementById) return document.getElementById(id).style.visibility = v?'visible':'hidden';
	if(document.layers) return document.layers[id].visibility = v?'show':'hide';
}