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: Overridden from OpenGLFrame
  Gets called on init or when the frame is remapped into its container.
code: def initgl(self):
      """Overridden from OpenGLFrame
      Gets called on init or when the frame is remapped into its container.
      """
      if (
          not hasattr(self, "_native_context")
          or self._native_context is None
      ):
          # Workaround to get OpenGLFrame.__context for reference here
          # if access would ever be needed from self._native_context.
          # FIXME: Context sharing this way seems unsupported
          self._native_context = vars(self).get(
              "_CanvasBackend__context", None
          )
  
      self.update_idletasks()
      gl.glClear(gl.GL_COLOR_BUFFER_BIT)
      gl.glClearColor(0.0, 0.0, 0.0, 0.0)
  
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 2 for calling the CanvasBackend obj's underlying member method code with example usage: obj.initgl() without return types