/* Courtesy of http://www.netlobo.com/div_hiding.html */
function toggleLayer(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)
	{
		if (elem.offsetWidth != 0 && elem.offsetHeight != 0) {
			vis.display = 'block';
		} else {
			vis.display = 'none';
		}
	}
	if (vis.display == '' || vis.display == 'block') {
		vis.display = 'none';
	} else {
		vis.display = 'block';
	}
}