code: func (h *Handler) SetGUISettings(tkn string, v map[string]interface{}) error {
  	logger := h.logger.Add("method", "SetGUISettings")
  
  	if !h.token.Check(tkn) {
  		logger.Warn("access denied")
  		return ErrAccessDenied
  	}
  
  	d, err := json.Marshal(&v)
  	if err != nil {
  		logger.Error(err.Error())
  		return ErrInternal
  	}
  
  	_, err = h.db.Exec(`
  		UPDATE settings 
  		   SET value = $1
  		 WHERE key=$2`, string(d), data.SettingGUI)
  	if err != nil {
  		logger.Error(fmt.Sprintf("failed to set gui settings: %v", err))
  		return ErrInternal
  	}
  
  	return nil
  }
docs: // SetGUISettings sets gui settings.