def draw_marked_items
      items = marked_items
      header_r.draw_marked_items count: items.size, size: items.inject(0) {|sum, i| sum += i.size}
    end
def draw_marked_items
      items = marked_items
      header_r.draw_marked_items count: items.size, size: items.inject(0) {|sum, i| sum += i.size}
    end
Update the header information concerning currently marked files or directories.