function CategoryOnOff(parentId, appUrl)
{
    var o = document.getElementById("panel_" + parentId);
    
    if (o != null)
    {
        if (o.style.display == "none")
        {
            o.style.display = "block";
            
            document.getElementById("triangle_" + parentId).src = appUrl + "/IMAGES/COURSES/triangle-icon-down.gif";
        }
        else
        {
            o.style.display = "none";
            
            document.getElementById("triangle_" + parentId).src = appUrl + "/IMAGES/COURSES/triangle-icon.gif";            
        }
    }
}