          self._initialized = not self._is_standalone
          self._root = parent if parent is not None else tk.Tk()
          self._master_frame = tk.Frame(self._root)
  
          self._taskbar = _Taskbar(self._master_frame, self._is_standalone)
  
          self._screen_dimensions = self._get_geometry()
          self._canvas = _PreviewCanvas(self._master_frame,
                                        self._taskbar.scale_var,
                                        self._screen_dimensions)
 
</s> remove         self._initialized = not self._is_standalone
 </s> add         self._initialized = False </s> remove                                       self._screen_dimensions)
 </s> add                                       self._screen_dimensions,
                                      self._is_standalone) </s> remove         self._image = _Image(self._taskbar.save_var)
 </s> add         self._image = _Image(self._taskbar.save_var, self._is_standalone) </s> remove         assert self._pathoutput is not None
        folders = [] if not os.path.exists(self._pathoutput) else [
            os.path.join(self._pathoutput, folder)
            for folder in os.listdir(self._pathoutput)
            if os.path.isdir(os.path.join(self._pathoutput, folder))]
 </s> add         folders = [] if not os.path.exists(self._output_path) else [
            os.path.join(self._output_path, folder)
            for folder in os.listdir(self._output_path)
            if os.path.isdir(os.path.join(self._output_path, folder))]
        self._taskbar = _Taskbar(self._master_frame, taskbar)
          self._initialized = not self._is_standalone
          self._root = parent if parent is not None else tk.Tk()
          self._master_frame = tk.Frame(self._root)
  
        self._taskbar = _Taskbar(self._master_frame, taskbar)
  
          self._screen_dimensions = self._get_geometry()
          self._canvas = _PreviewCanvas(self._master_frame,
                                        self._taskbar.scale_var,
                                        self._screen_dimensions)
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