function shiftOpacity(id, millisec) {
		if (navigator.appName.indexOf("Microsoft")!= -1) {
			millisec = Math.round(millisec / 2);
		}
    //if an element is invisible, make it visible, else make it ivisible
    if(document.getElementById(id).style.opacity == 0 || (navigator.appName.indexOf("Microsoft")!= -1 && document.getElementById(id).filters.alpha.opacity == 0)) {
				document.getElementById(id).style.height = 'auto';
				document.getElementById(id).style.visibility = 'visible';
        opacity(id, 0, 100, millisec);
    } else {
        opacity(id, 100, 0, millisec);
    }
} 

function opacity(id, opacStart, opacEnd, millisec) {
    //speed for each frame
    var speed = Math.round(millisec / 100);
    var timer = 0;

    //determine the direction for the blending, if start and end are the same nothing happens
    if(opacStart > opacEnd) {
        for(i = opacStart; i >= opacEnd; i--) {
            setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
            timer++;
        }
				setTimeout("zeroHeight('" + id + "')",(timer * speed));
    } else 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 + ")";
} 

function zeroHeight(id) {
	document.getElementById(id).style.height = '0px';
	document.getElementById(id).style.visibility = 'hidden';
}