                  old_value = self.config.config[section][item]
                  if new_value != old_value:
                      logger.trace("Updating config: %s, %s from %s to %s",
                                   section, item, old_value, new_value)
                      self.config.config[section][item] = str(value.get())
  
      def get_config_dicts(self):
          """ Hold a custom config dict for the config """
          config_dicts = dict()
          for section in self.config.config.sections():
 
</s> remove                 new_value = str(value.get())
 </s> add                 try:
                    new_value = str(value.get())
                except tk.TclError as err:
                    # When manually filling in text fields, blank values will
                    # raise an error on numeric datatypes so return 0
                    logger.debug("Error getting value. Defaulting to 0. Error: %s", str(err))
                    new_value = str(0)
                    self.config.config[section][item] = new_value
                  old_value = self.config.config[section][item]
                  if new_value != old_value:
                      logger.trace("Updating config: %s, %s from %s to %s",
                                   section, item, old_value, new_value)
                    self.config.config[section][item] = new_value
  
      def get_config_dicts(self):
          """ Hold a custom config dict for the config """
          config_dicts = dict()
          for section in self.config.config.sections():
keep keep keep keep replace keep keep keep keep keep
 Bugfix: Preview Tool - empty tk_var string

- Replace empty tk_vars with 0 for numerical values 
tools/preview.py