Bug 32254 [Viewers] AbstractTreeViewer uses HashSet to remember expansion state
I20030216 The custom hash table should be used instead. Otherwise expansion state may be lost due to a different equals implementation of the element and the IElementComparer.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/TreeViewer.java
* @return the tree control
 */
public Tree getTree() {
	return tree;
}
/* (non-Javadoc)
 * Method declared in AbstractTreeViewer.
 */
protected Item newItem(Widget parent, int flags, int ix) {
	TreeItem item;
	if (ix >= 0) {
		if (parent instanceof TreeItem)
			item = new TreeItem((TreeItem) parent, flags, ix);
		else
			item = new TreeItem((Tree) parent, flags, ix);
	} else {
		if (parent instanceof TreeItem)
			item = new TreeItem((TreeItem) parent, flags);
		else
			item = new TreeItem((Tree) parent, flags);
	}
	return item;
}
/* (non-Javadoc)
 * Method declared in AbstractTreeViewer.
 */
protected void removeAll(Control widget) {
	((Tree) widget).removeAll();
}
/* (non-Javadoc)