mikutter

↓のようなモンキーパッチで動きました（引数を追加してまわっただけ）

module Gtk::FormDSL
  def fileselect(label, config, _current=Dir.pwd, dir: _current, title: label.to_s, shortcuts: nil)
    fsselect(label, config, dir: dir, action: Gtk::FileChooser::ACTION_OPEN, title: title, shortcuts: shortcuts)
  end

  def dirselect(label, config, _current=Dir.pwd, dir: _current, title: label.to_s, shortcuts: nil)
    fsselect(label, config, dir: dir, action: Gtk::FileChooser::ACTION_SELECT_FOLDER, title: title, shortcuts: shortcuts)
  end

  def fsselect(label, config, dir: Dir.pwd, action: Gtk::FileChooser::ACTION_OPEN, title: label, shortcuts: nil)
    container = input(label, config)
    input = container.children.last.children.first
    button = Gtk::Button.new(Plugin[:settings]._('参照'))
    container.pack_start(button, false)
    button.signal_connect(:clicked, &gen_fileselect_dialog_generator(title, action, dir, config: config, shortcuts: shortcuts, &input.method(:text=)))
    container
  end

  def gen_fileselect_dialog_generator(title, action, dir, config:, shortcuts: nil, &result_callback)
    ->(widget) do
      dialog = Gtk::FileChooserDialog.new(title,
                                          widget.get_ancestor(Gtk::Window),
                                          action,
                                          nil,
                                          [Gtk::Stock::CANCEL, Gtk::Dialog::RESPONSE_CANCEL],
                                          [Gtk::Stock::OPEN, Gtk::Dialog::RESPONSE_ACCEPT])
      dialog.current_folder = File.expand_path(dir)
      shortcuts.to_a.select { |dir|
        !dialog.shortcut_folders.include?(dir)
      }.each { |dir|
        begin
          dialog.add_shortcut_folder(dir)
        rescue => e
          puts e
          puts e.backtrace
        end
      }
      dialog.ssc_atonce(:response, &gen_fs_dialog_response_callback(config, &result_callback))
      dialog.show_all
      false
    end
  end
end

書いてから思いましたが、uwm-hommageの https://github.com/moguno/mikutter-uwm-hommage/blob/master/penguin.rb#L33 周辺にあるfilterやpreview_widgetも欲しくなってきますね……

パッチにしてほしいンゴですね