          logger.info("Updating config at: '%s'", self.configfile)
          f_cfgfile = open(self.configfile, "w")
          self.config.write(f_cfgfile)
          f_cfgfile.close()
  
      def validate_config(self):
          """ Check for options in default config against saved config
              and add/remove as appropriate """
          logger.debug("Validating config")
          if self.check_config_change():
 
</s> remove                     self.config.config[section][item] = str(value.get())
 </s> add                     self.config.config[section][item] = new_value </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)
        logger.debug("Updated config at: '%s'", self.configfile)
          logger.info("Updating config at: '%s'", self.configfile)
          f_cfgfile = open(self.configfile, "w")
          self.config.write(f_cfgfile)
          f_cfgfile.close()
        logger.debug("Updated config at: '%s'", self.configfile)
  
      def validate_config(self):
          """ Check for options in default config against saved config
              and add/remove as appropriate """
          logger.debug("Validating config")
          if self.check_config_change():
keep keep keep add keep keep keep keep keep keep
 Bugfix: Preview Tool - empty tk_var string

- Replace empty tk_vars with 0 for numerical values 
lib/config.py