var categories = new Array();


function addCategory(cat) {
    categories.push(cat);
    if (categories.length > 1)
    document.getElementById(cat).style.display = "none";
}


function showCategory(cat) {
    hideAllCategoryDivs();
    document.getElementById(cat).style.display = "block";
}


function hideAllCategoryDivs() {
    for (var i = 0; i < categories.length; i++) {
        document.getElementById(categories[i]).style.display = "none";
    }
}