# File lib/sup/mode.rb, line 55
  def help_text
    used_keys = {}
    ancestors.map do |klass|
      km = @@keymaps[klass] or next
      title = "Keybindings from #{Mode.make_name klass.name}"
      s = "\#{title}\n\#{'-' * title.display_length}\n\n\#{km.help_text used_keys}\n"
      begin
        used_keys.merge! km.keysyms.to_boolean_h
      rescue ArgumentError
        raise km.keysyms.inspect
      end
      s
    end.compact.join "\n"
  end