function showSub(ix) {
	getItem("sub"+ix).style.visibility = "visible";
	opacity("sub"+ix, 90, 100, 1000);
}
function hideSub(ix) {
	getItem("sub"+ix).style.visibility = "hidden";
}

function getItem(id) {
	return document.getElementById(id)
}
function opacity(id, opacStart, opacEnd, millisec) {

    var speed = Math.round(millisec / 100); //speed for each frame
    var timer = 0;
	if(opacStart < opacEnd) {
        for(i = opacStart; i <= opacEnd; i++)
            {
            setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
            timer++;
        }
    } 
} 
//change the opacity for different browsers
function changeOpac(opacity, id) {
    var object = document.getElementById(id).style;
    object.opacity = (opacity / 100);
    object.MozOpacity = (opacity / 100);
    object.KhtmlOpacity = (opacity / 100);
    object.filter = "alpha(opacity=" + opacity + ")";
}