nullcategories

function categoryChecklist( $child_of, $selected_cats )
    {
        $walker = new Walker_Category_Checklist;
        $child_of = (int) $child_of;

        $args = array();
        $args['selected_cats'] = $selected_cats;
        $args['popular_cats'] = array();
        $categories = get_categories( "child_of=$child_of&hierarchical=0&hide_empty=0" );

        $null_categories = array();
        for ( $i = 0; isset($categories[$i]); $i++ ) {
            if (($categories[$i]->category_count) ) {
                $null_categories[] = $categories[$i];
                unset($categories[$i]);
            }
        }
        echo call_user_func_array(array(&$walker, 'walk'), array($null_categories, 0, $args));
    }