// nasconde/rende visibile il contenuto del div whichLayer
function ddToggleLayer( whichLayer )
{
	var elem, vis;
	if( document.getElementById ) // this is the way the standards work
		elem = document.getElementById( whichLayer );
	else if( document.all ) // this is the way old msie versions work
		elem = document.all[whichLayer];
	else if( document.layers ) // this is the way nn4 works
		elem = document.layers[whichLayer];
	vis = elem.style;
	// if the style.display value is blank we try to figure it out here
	if(vis.display==''&&elem.offsetWidth!=undefined&&elem.offsetHeight!=undefined)
		vis.display = (elem.offsetWidth!=0&&elem.offsetHeight!=0)?'block':'none';
	vis.display = (vis.display==''||vis.display=='block')?'none':'block';
}


// SIMILE A toggleLayer
function show_div(div_id) {
    // hide all the divs
    document.getElementById('the_div_1').style.display = 'none'; 
    document.getElementById('the_div_2').style.display = 'none';
    document.getElementById('the_div_3').style.display = 'none';

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