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: Callback when the window gets closed.
  Destroy the VisPy canvas by calling close on it.
code: def destroy(self):
      """Callback when the window gets closed.
      Destroy the VisPy canvas by calling close on it.
      """
      self._vispy_canvas.close()
  
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 29 for calling the CanvasBackend obj's underlying member method code with example usage: obj.destroy() without return types