code: def _show_selection(self, text, bbox):
          
          x, y, width, height = bbox
  
          textw = self._font.measure(text)
  
          canvas = self._canvas
          canvas.configure(width=width, height=height)
          canvas.coords(canvas.text, width - textw, height / 2 - 1)
          canvas.itemconfigure(canvas.text, text=text)
          canvas.place(in_=self._calendar, x=x, y=y)
docs: Configure canvas for a new selection.