          tkinter.Frame or ``None``
              The dummy master frame for Linux systems, otherwise ``None``
          """
          if platform.system().lower() == "linux":
              retval = tk.Frame()
              retval.option_add("*foreground", "black")
          else:
              retval = None
          return retval
  
      def _remove_dummy_master(self):
 
</s> remove     def _remove_dummy_master(self):
 </s> add     def _remove_dummy_master(self) -> None: </s> remove         if platform.system().lower() != "linux":
 </s> add         if platform.system().lower() != "linux" or self._dummy_master is None: </s> remove         retval = dict()
 </s> add         retval = {} </s> remove     def run(self):
 </s> add     def run(self) -> None: </s> remove                       if os.path.getmtime(fname) > self._previewcache["modified"]]
 </s> add                       if os.path.getmtime(fname) > cast(float, self._previewcache["modified"])]
            frame = tk.Frame()
            frame.option_add("*foreground", "black")
            retval: Optional[tk.Frame] = frame
          tkinter.Frame or ``None``
              The dummy master frame for Linux systems, otherwise ``None``
          """
          if platform.system().lower() == "linux":
            frame = tk.Frame()
            frame.option_add("*foreground", "black")
            retval: Optional[tk.Frame] = frame
            frame = tk.Frame()
            frame.option_add("*foreground", "black")
            retval: Optional[tk.Frame] = frame
          else:
              retval = None
          return retval
  
      def _remove_dummy_master(self):
keep keep keep keep replace replace keep keep keep keep keep
 Bugfix: Preview for extract in batch mode 
lib/gui/utils.py