//layer visibility functions
function toggleLayer(obj) {
    if(document.getElementById(obj).style.visibility == "visible") {
	    document.getElementById(obj).style.visibility = "hidden";
	    document.getElementById(obj).style.display = "none";
    }
    else {
document.getElementById(obj).style.visibility = "visible";
	    document.getElementById(obj).style.display = "";
    }
}
function hideLayer(obj) {
    document.getElementById(obj).style.visibility = "hidden";
    document.getElementById(obj).style.display = "none";
} 
function showLayer(obj) {
	document.getElementById(obj).style.visibility = "visible";
	document.getElementById(obj).style.display = "";
}