function overlay(id) {
    var el = document.getElementById(id);
    el.style.display = (el.style.display != "block") ? "block" : "none";
}

function toggleLayer(img, whichLayer)
{
    var obj = $(whichLayer);
    if (obj.style.display == 'none') {
        new Effect.Appear(obj, {duration:0.2 });
        $(img).src = '/image/new/exclude.gif';
    } else {
        new Effect.Fade(obj, {duration:0.1 });
        $(img).src = '/image/new/include.gif'
    }
}
function toggleLayerWithNoEffect(img, whichLayer)
{
    var obj = $(whichLayer);
    if (obj.style.display == 'none') {
        obj.style.display='block';
    } else {
        obj.style.display='none';
    }
}

function toggleLayerWithTextLink(divToToggle,linkToChangeText,textOn,textOff){
    var obj = $(divToToggle);
    if (obj.style.display == 'none') {
        new Effect.Appear(obj, {duration:0.2 });
        linkToChangeText.innerHTML=textOff;
    } else {
        new Effect.Fade(obj, {duration:0.1 });
        linkToChangeText.innerHTML=textOn;
    }
}


function toggleHelpLayer(nameOfHelpImg, nameOfHelpDiv)
{
    var obj = $(nameOfHelpDiv);
    if (obj.style.display == 'none') {
        new Effect.BlindDown(obj, {duration:0.2})
        $(nameOfHelpImg).src = '/image/new/little-round-close.gif';
    } else {
        new Effect.BlindUp(obj, {duration:0.1 });
        $(nameOfHelpImg).src = '/image/new/little-round-info.gif'
    }
}

function toggleLayerImage(img, whichLayer, imageon, imageoff)
{
    var obj = document.getElementById(whichLayer);
    obj.style.display = (obj.style.display == 'none') ? new Effect.Appear($(obj), {duration:0.2 }) : new Effect.Fade($(obj), {duration:0.1 })
    if (obj.style.display == 'block') img.src = imageon
    else img.src = imageoff
}