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++;
	    if (i == opacStart)
	    {
		    setTimeout("document.getElementById('"+ id + "').style.visibility='visible';",(timer * speed));
		    timer++;
	    }
        }
		if (opacEnd == 0)
			setTimeout("document.getElementById('"+ id + "').style.visibility='hidden';",(timer * speed));
    } else if(opacStart < opacEnd) {        
		for(i = opacStart; i <= opacEnd; i++)
            {
            setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
            timer++;
	    if (i == opacStart)
	    {
		    setTimeout("document.getElementById('"+ id + "').style.visibility='visible';",(timer * speed));
		    timer++;
	    }
        }		
    }
}

function hide(id, milisec)
{
    if (milisec > 0)
	opacity(id, 100, 0, milisec);
    else
    {
	changeOpac(0, id);
	document.getElementById(id).style.visibility='hidden';
    }
    return false;
}

function show(id, milisec)
{    
	//document.getElementById(id).style.visibility="hidden";
	//chanceOpac(0, id);
	//document.getElementById(id).style.visibility="visible";
    if (milisec > 0)
	opacity(id, 0, 100, milisec);
    else
    {
	changeOpac(100, id);
	document.getElementById(id).style.visibility='visible';
    }
    return false;
}

//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 shiftOpacity(id, millisec) {
    //if an element is invisible, make it visible, else make it ivisible
    if(document.getElementById(id).style.opacity == 0) {
        opacity(id, 0, 100, millisec);
    } else {
        opacity(id, 100, 0, millisec);
    }
}