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
filters = null;
			refresh();
		}
	}
	/**
	 * Ensures that the given element is visible, scrolling the viewer if
	 * necessary. The selection is unchanged.
	 * 
	 * @param element
	 *            the element to reveal
	 */
	public abstract void reveal(Object element);
	/*
	 *  (non-Javadoc)
	 * @see org.eclipse.jface.viewers.ContentViewer#setContentProvider(org.eclipse.jface.viewers.IContentProvider)
	 */
	public void setContentProvider(IContentProvider provider) {
		assertContentProviderType(provider);
		super.setContentProvider(provider);
	}
	/**
	 * Assert that the content provider is of one of the
	 * supported types.
	 * @param provider
	 */
	protected void assertContentProviderType(IContentProvider provider) {
		Assert.isTrue(provider instanceof IStructuredContentProvider);
	}
	/*
	 *  (non-Javadoc)