Bug 15844 [Exception Handling] SelectionChange events and NPE
Build 20020508 Due to new global actions there are now more objects listening to selection changes send out by a JFace viewer. We now had the case that one of the listener generated a NPE. As a result all listeners registered after that one didn't receive the selection change event. StructuredViewers should be more fault tolorant to exceptions when informing listeners.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/StructuredViewer.java
* from element to widgets is removed and the new mapping is added. 
 * If fullmap is <code>false</code> then only the new map gets installed.
 * Installing only the new map is necessary in cases where only
 * the order of elements changes but not the set of elements.
 * <p>
 * This method is internal to the framework; subclassers should not call
 * this method.
 * </p>
 *
 * @param item
 * @param element the element
 * @param fullMap <code>true</code> if mappings are added and removed,
 *   and <code>false</code> if only the new map gets installed
 */
protected abstract void doUpdateItem(
	Widget item,
	Object element,
	boolean fullMap);
/**
 * Returns the result of running the given elements through the filters.
 *
 * @param elements the elements to filter
 * @return only the elements which all filters accept
 */
protected Object[] filter(Object[] elements) {
	if (filters != null) {
		ArrayList filtered = new ArrayList(elements.length);
		Object root = getRoot();
		for (int i = 0; i < elements.length; i++) {
			boolean add = true;