var VisibleCategories = {};

function ToggleShowArticles(id){

    if(VisibleCategories[id]){
        //Hide Category
        Utilities.RemoveClass('heading:' + id, 'visible');
        Utilities.RemoveClass('articles:' + id, 'visible');
        delete VisibleCategories[id];
        }
    else{
        //Show Category
        Utilities.AddClass('heading:' + id, 'visible');
        Utilities.AddClass('articles:' + id, 'visible');
        VisibleCategories[id] = true;
        }
    }