function overButton(btn_id)
{
	btn = document.getElementById(btn_id);
	if (btn == null)
	{
		alert('Could not locate entity "' + btn_id + '" in document.');
		return;
	}
	btn.setAttribute("class", "buttonOn"); 
	//btn.class = 'buttonOn';
}

function outButton(btn_id)
{
	btn = document.getElementById(btn_id);
	if (btn == null)
	{
		alert('Could not locate entity "' + btn_id + '" in document.');
		return;
	}
	btn.setAttribute("class", "buttonOff"); 
	//btn.class = 'buttonOff';
}