Bug 299438 [CommonNavigator] CNF viewer state non properly reset when NCEs are activated or deactivated
The map of the objects to the NCEs should be reset whenever the NCEs associated with the viewer to change to avoid having stale label information. This has shown up when looking at the CNF tests that change the viewer.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/StructuredViewer.java
}
	
	/**
	 * Configures whether this structured viewer uses an internal hash table to
	 * speeds up the mapping between elements and SWT items. This must be called
	 * before the viewer is given an input (via <code>setInput</code>).
	 * 
	 * @param enable
	 *            <code>true</code> to enable hash lookup, and
	 *            <code>false</code> to disable it
	 */
	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 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) {