function show_div(div_id) {
	// hide all the divs
	document.getElementById('the_div_1').style.visibility = 'hidden';

	// show the requested div
	document.getElementById(div_id).style.visibility = 'visible';
	}
	
function hide_div(div_id) {
	// hide all the divs
	document.getElementById('the_div_1').style.visibility = 'hidden';

	// show the requested div
	document.getElementById(div_id).style.visibility = 'hidden';
	}