A widget that implements this interface contains {@link com.google.gwt.user.client.ui.TreeItem items} and can operate them.

abstract class HasTreeItems {

 /**
  * Adds a simple tree item containing the specified html.
  *
  * @param itemHtml the html of the item to be added
  * @return the item that was added
  */
 TreeItem addSafeHtmlItem(SafeHtml itemHtml);

 /**
  * Adds an tree item.
  *
  * @param item the item to be added
  */
 void addItem(TreeItem item);

 /**
  * Adds an item wrapped by specified {@link IsTreeItem}.
  *
  * @param isItem the wrapper of item to be added
  */
 void addIsTreeItem(IsTreeItem isItem);

 /**
  * Adds a new tree item containing the specified widget.
  *
  * @param widget the widget to be added
  * @return the new item
  */
 TreeItem addWidgetItem(Widget widget);

 /**
  * Adds a simple tree item containing the specified text.
  *
  * @param itemText the text of the item to be added
  * @return the item that was added
  */
 TreeItem addTextItem(String itemText);

 /**
  * Removes an item.
  *
  * @param item the item to be removed
  */
 void removeItem(TreeItem item);

 /**
  * Removes an item.
  *
  * @param isItem the wrapper of item to be removed
  */
 void removeIsTreeItem(IsTreeItem isItem);

 /**
  * Removes all items.
  */
 void removeItems();

}