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
* @param element The element being decorated.
	 * @param labelProvider ILabelProvider the labelProvider for the receiver.
	 */
	void buildLabel(ViewerLabel updateLabel, Object element,ILabelProvider labelProvider){
			updateLabel.setText(labelProvider.getText(element));
			updateLabel.setImage(labelProvider.getImage(element));
	}
	/**
	 * Get the ColorAndFontCollector for the receiver.
	 * @return ColorAndFontCollector 
	 * @since 3.1
	 */
	protected ColorAndFontCollector getColorAndFontCollector() {
		return colorAndFontCollector;
	}
	
	protected void handleDispose(DisposeEvent event) {
		super.handleDispose(event);
		sorter = null;
		comparer = null;
		if (filters != null)
			filters.clear();
		elementMap = newHashtable(1);
		openListeners.clear();
		doubleClickListeners.clear();
		colorAndFontCollector.clear();
		postSelectionChangedListeners.clear();
	}
}