var submenu = [];
var initialized = false;
function init() {
	submenu[0] = document.getElementById('submenu_0');
	submenu[1] = document.getElementById('submenu_1');
	submenu[2] = document.getElementById('submenu_2');
	submenu[3] = document.getElementById('submenu_3');		
	initialized = true;
};
function showover(id) {
	if (! initialized) init();
	for (i=0; i<4; i++) {
 	  if (i != id) {
            submenu[i].style.display = 'none';
			document.getElementById('menu_'+i).className='menu-off';
		} else {
			submenu[i].style.display = 'block';
			document.getElementById('menu_'+i).className='menu-on';
		}		
	};
};