Bug 122756 [Viewers] Support for TreePath based content providers
Now that the JFace tree viewer supports the notion of a tree path, it would be benefitial if this information was made available to content providers and label providers. The particular scenario that requires this is team views that include change sets. A view can display multiple change sets and a single model element may be included in multiple change sets. In 3.2, we are using the common navigator framework to allow model providers to display their models in a team operation. Having a tree path based content provider would allow the logical model display to be intermixed with change sets. Without this support, team providers would most likely need to support two views, one which shows resources and change sets and another that shows the effects of the operation on the logical model.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/StructuredViewer.java
*/
	public void setUseHashlookup(boolean enable) {
		Assert.isTrue(getInput() == null,
				"Can only enable the hash look up before input has been set");
		if (enable) {
			elementMap = newHashtable(CustomHashtable.DEFAULT_CAPACITY);
		} else {
			elementMap = null;
		}
	}
	/**
	 * Sets the comparator to use for comparing elements, or <code>null</code>
	 * to use the default <code>equals</code> and <code>hashCode</code>
	 * methods on the elements themselves.
	 * 
	 * @param comparer
	 *            the comparator to use for comparing elements or
	 *            <code>null</code>
	 */
	public void setComparer(IElementComparer comparer) {
		this.comparer = comparer;
		if (elementMap != null) {
			elementMap = new CustomHashtable(elementMap, comparer);
		}
	}
	/**
	 * Hook for testing.
	 * @param element
	 * @return Widget
	 */