          super().__init__(parent)
          self.pack(side=tk.RIGHT, anchor=tk.N, fill=tk.BOTH, expand=True)
          self.config_tools = config_tools
  
          self._tabs = dict()
          self._build_tabs()
          self._build_sub_tabs()
          self._add_patch_callback(patch_callback)
          logger.debug("Initialized %s", self.__class__.__name__)
  
 
</s> remove         self._tk_vars = dict()
 </s> add         self._tk_vars = {} </s> remove         self.source = list()  # Source images, filenames + detected faces
 </s> add         self.source = []  # Source images, filenames + detected faces </s> remove         self.destination = list()  # Swapped + patched images
 </s> add         self.destination = []  # Swapped + patched images </s> remove         self._faces = dict()
 </s> add         self._faces = {} </s> remove         defaults = {opt: self._format_to_display(d_locals["selected_{}".format(opt)])
 </s> add         defaults = {opt: self._format_to_display(d_locals[f"selected_{opt}"])
        self._tabs = {}
          super().__init__(parent)
          self.pack(side=tk.RIGHT, anchor=tk.N, fill=tk.BOTH, expand=True)
          self.config_tools = config_tools
  
        self._tabs = {}
          self._build_tabs()
          self._build_sub_tabs()
          self._add_patch_callback(patch_callback)
          logger.debug("Initialized %s", self.__class__.__name__)
  
keep keep keep keep replace keep keep keep keep keep
 bugfix: Preview Tool, ensure all config items are written 
tools/preview/preview.py