def ctrl_a
      mark = marked_items.size != (items.size - 2)  # exclude . and ..
      items.each {|i| i.toggle_mark unless i.marked? == mark}
      draw_items
      draw_marked_items
      move_cursor current_row
    end
def ctrl_a
      mark = marked_items.size != (items.size - 2)  # exclude . and ..
      items.each {|i| i.toggle_mark unless i.marked? == mark}
      draw_items
      draw_marked_items
      move_cursor current_row
    end
Mark or unmark "a"ll files and directories.