          return slider
  
      def _add_interpolator_radio(self) -> None:
          """ Add a radio box to choose interpolator """
          frame = tk.Frame(self)
          for text, mode in self._interpolators:
              radio = tk.Radiobutton(frame, text=text, value=mode, variable=self.interpolator_var)
              radio.pack(side=tk.LEFT, anchor=tk.W)
          self.interpolator_var.set(cv2.INTER_NEAREST)
          frame.pack(side=tk.RIGHT)
 
</s> remove         button = tk.Button(self,
 </s> add         button = tk.Button(self._frame,
        frame = tk.Frame(self._frame)
          return slider
  
      def _add_interpolator_radio(self) -> None:
          """ Add a radio box to choose interpolator """
        frame = tk.Frame(self._frame)
          for text, mode in self._interpolators:
              radio = tk.Radiobutton(frame, text=text, value=mode, variable=self.interpolator_var)
              radio.pack(side=tk.LEFT, anchor=tk.W)
          self.interpolator_var.set(cv2.INTER_NEAREST)
          frame.pack(side=tk.RIGHT)
keep keep keep keep replace keep keep keep keep keep
 GUI - Preview updates
  - Training preview. Embed preview pop-out window
  - Bugfix - convert/extract previews 
lib/training/preview_tk.py