code: def _mpl_modifiers(self, controller=None):
      if controller is None:
          surface = self.get_native().get_surface()
          is_over, x, y, event_state = surface.get_device_position(
              self.get_display().get_default_seat().get_pointer()
          )
      else:
          event_state = controller.get_current_event_state()
      mod_table = [
          ("ctrl", Gdk.ModifierType.CONTROL_MASK),
          ("alt", Gdk.ModifierType.ALT_MASK),
          ("shift", Gdk.ModifierType.SHIFT_MASK),
          ("super", Gdk.ModifierType.SUPER_MASK),
      ]
      return [name for name, mask in mod_table if event_state & mask]
  
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 14 for calling the FigureCanvasGTK4 obj's underlying member method code with example usage: obj._mpl_modifiers(controller) and returns: unknown