anchor.diff:    Map attribute_callbacks = {
       'default'  : (attr_name, self) => self.attribute_callbacks_collection['write_property_to_dom'](attr_name, self),
       'disabled' : (attr_name, self) {
  -      if(self.disabled == 'disabled') {
  -        self.event_locks.add(#any); 
  +      if(self.disabled) {
  +        self.event_locks.add(#any);
           self.behave('disable');
         } else {
           self.behave('enable');
  
positive.code:     * it should then be possible to press letter keys to navigate the options list without
      * opening the selectbox. That's native browser behavior for <select> element and that's
      * what's being emulated here.
      * 
      * Note the use of keypress_stack. If user presses "a" and "b" within 1 second of each other
      * then the stack is going to contain "ab" and we'll be looking for the first option
      * which has display_value that starts with "ab", then setting it as current option
  
negative.code: 
      this.options = new LinkedHashMap.from(parsed_json);
    }
  
    /** This methd is called not once, but every time we fetch new options from the server,
      * because the newly added option elements are not being monitored by the previously
      * created listener.
  