function showHideCategories(showhide) {
        if (showhide==1) {
            cat_table = document.getElementById( 'category_table' );
            cat_table.style.visibility = 'visible';
            cat_table.style.display    = 'block';
        } else {
            cat_table = document.getElementById( 'category_table' );
            cat_table.style.visibility = 'hidden';
            cat_table.style.display    = 'none';
        } 
        
    }