class_docstr: Subclass of `.TimerBase` using GTK timer events.
class_docstr_tok: ["Subclass","of","`",".TimerBase","`","using","GTK","timer","events","."]
code: def _on_timer(self):
      super()._on_timer()
  
      # Gtk timeout_add() requires that the callback returns True if it
      # is to be called again.
      if self.callbacks and not self._single:
          return True
      else:
          self._timer = None
          return False
  
imports: import logging
  import sys
  import matplotlib
  from matplotlib import _api, backend_tools, cbook
  from matplotlib._pylab_helpers import Gcf
  from matplotlib.backend_bases import _Backend, FigureCanvasBase, FigureManagerBase, NavigationToolbar2, TimerBase
  from matplotlib.backend_tools import Cursors
  import gi
  from gi.repository import Gdk, Gio, GLib, Gtk
label_desc: Use image node_id 5 for calling the TimerGTK obj's underlying member method code with example usage: obj._on_timer() and returns: True, False