/**
   * Initializes custom contact action buttons.
   *
   * @param contactActionButtons the list of buttons to initialize
   * @param gridX the X grid of the first button
   * @param xBounds the x bounds of the first button
   * @return the new grid X coordinate after adding all the buttons
   */
  private int initGroupActionButtons(
      Collection<SIPCommButton> contactActionButtons, int gridX, int xBounds) {
    // Reinit the labels to take the whole horizontal space.
    addLabels(gridX + contactActionButtons.size());

    Iterator<SIPCommButton> actionsIter = contactActionButtons.iterator();
    while (actionsIter.hasNext()) {
      final SIPCommButton actionButton = actionsIter.next();

      // We need to explicitly remove the buttons from the tooltip manager,
      // because we're going to manager the tooltip ourselves in the
      // DefaultTreeContactList class. We need to do this in order to have
      // a different tooltip for every button and for non button area.
      ToolTipManager.sharedInstance().unregisterComponent(actionButton);

      if (customActionButtonsUIGroup == null)
        customActionButtonsUIGroup = new LinkedList<JButton>();

      customActionButtonsUIGroup.add(actionButton);

      xBounds += addButton(actionButton, ++gridX, xBounds, false);
    }

    return gridX;
  }