code: public void setSelectedInternalItem(User user) {
  		User internalUser = null;
  		int index = getIndexOf(user);
  		if (index != -1) {
  			internalUser = getElementAt(index);
  		} else if (getSize() > 0) {
  			internalUser = getElementAt(0);
  		}
  
  		setSelectedItemImpl(internalUser);
  	}
docs: Sets the selected item as the actual internal item with the same id as the provided user.
  
  @param user the new selected internal item