code: def _show_shortcuts_dialog(self):
      dialog = Gtk.MessageDialog(
          self._figure.canvas.get_toplevel(),
          0,
          Gtk.MessageType.INFO,
          Gtk.ButtonsType.OK,
          self._get_help_text(),
          title="Help",
      )
      dialog.run()
      dialog.destroy()
  
imports: import functools
  import logging
  import os
  from pathlib import Path
  import matplotlib
  from matplotlib import _api, backend_tools, cbook
  from matplotlib.backend_bases import ToolContainerBase, CloseEvent, KeyEvent, LocationEvent, MouseEvent, ResizeEvent
  from gi.repository import Gio, GLib, GObject, Gtk, Gdk
  from .None import _backend_gtk
  from ._backend_gtk import _BackendGTK, _FigureCanvasGTK, _FigureManagerGTK, _NavigationToolbar2GTK, TimerGTK
label_desc: Use image node_id 4 for calling the HelpGTK3 obj's underlying member method code with example usage: obj._show_shortcuts_dialog() without return types