code: def key_press_event(self, controller, keyval, keycode, state):
      KeyEvent(
          "key_press_event",
          self,
          self._get_key(keyval, keycode, state),
          *self._mpl_coords(),
      )._process()
      return True
  
imports: import functools
  import io
  import os
  import matplotlib
  from matplotlib import _api, backend_tools, cbook
  from matplotlib.backend_bases import ToolContainerBase, KeyEvent, LocationEvent, MouseEvent, ResizeEvent, CloseEvent
  from gi.repository import Gio, GLib, Gtk, Gdk, GdkPixbuf
  from .None import _backend_gtk
  from ._backend_gtk import _BackendGTK, _FigureCanvasGTK, _FigureManagerGTK, _NavigationToolbar2GTK, TimerGTK
label_desc: Use image node_id 8 for calling the FigureCanvasGTK4 obj's underlying member method code with example usage: obj.key_press_event(controller, keyval, keycode, state) and returns: True