class_docstr: Tkinter backend for Canvas abstract class.
  Uses pyopengltk.OpenGLFrame as the internal tk.Frame instance that
  is able to receive OpenGL draw commands and display the results,
  while also being placeable in another Toplevel window.
class_docstr_tok: ["Tkinter","backend","for","Canvas","abstract","class",".","Uses","pyopengltk.OpenGLFrame","as","the","internal","tk.Frame","instance","that","is","able","to","receive","OpenGL","draw","commands","and","display","the","results",",","while","also","being","placeable","in","another","Toplevel","window","."]
docstr: Invoke a redraw
  
  Delay this by letting Tk call it later, even a delay of 0 will do.
  Doing this, prevents EventEmitter loops that are caused
  by wanting to draw too fast.
code: def _vispy_update(self):
      """Invoke a redraw
  
      Delay this by letting Tk call it later, even a delay of 0 will do.
      Doing this, prevents EventEmitter loops that are caused
      by wanting to draw too fast.
      """
      self.after(0, self._delayed_update)
  
imports: from __future__ import division
  from time import sleep
  import warnings
  from ..base import BaseApplicationBackend, BaseCanvasBackend, BaseTimerBackend
  from ...util import keys
  from ...util.ptime import time
  from ...gloo import gl
label_desc: Use image node_id 27 for calling the CanvasBackend obj's underlying member method code with example usage: obj._vispy_update() without return types