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/CustomHashtable.java
private static final EmptyEnumerator emptyEnumerator = new EmptyEnumerator();
	/**
	 * Constructs a new Hashtable using the default capacity
	 * and load factor.
	 */
	public CustomHashtable() {
		this(13);
	}
	/**
	 * Constructs a new Hashtable using the specified capacity
	 * and the default load factor.
	 *
	 * @param capacity the initial capacity
	 */
	public CustomHashtable(int capacity) {
		this(capacity, null);
	}
	/**
	 * Constructs a new hash table with the default capacity and the given
	 * element comparer.
	 *
	 * @param comparer the element comparer to use to compare keys and obtain
	 *   hash codes for keys, or <code>null</code>  to use the normal 
	 *   <code>equals</code> and <code>hashCode</code> methods
	 */
	public CustomHashtable(IElementComparer comparer) {
		this(13, comparer);
	}
	/**