Bug 135284 [Viewers] API: need to add methods to StructuredViewer to support ViewerComparator
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/StructuredViewer.java
elementMap = newHashtable(CustomHashtable.DEFAULT_CAPACITY);
		} else {
			elementMap = null;
		}
	}
	/**
	 * Sets the comparer 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 comparer 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
	 */
	public Widget testFindItem(Object element) {
		return findItem(element);
	}
	/**
	 * Hook for testing.