// reveals the given div ID
	function showdiv(divid) {
		document.getElementById(divid).style.display='block';
	}

	// hides the given div ID
	function hidediv(divid) {
		document.getElementById(divid).style.display='none';
	}

	// given a menu number (i.e. 1 - 4) will show the appropriate div and hide all others
	function switchToMenu(num) {
	
		// close all menus
		hidediv('menu1');
		hidediv('menu2');
		hidediv('menu3');
		hidediv('menu4');

		// open the div for the selected menu
		showdiv('menu'+num);
	}