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/Viewer.java
* Method declared on ISelectionProvider.
 */
public void removeSelectionChangedListener(ISelectionChangedListener listener) {
	selectionChangedListeners.remove(listener);
}
/**
 * Scrolls the viewer's control down by one item from the given
 * display-relative coordinates.  Returns the newly revealed Item,
 * or <code>null</code> if no scrolling occurred or if the viewer
 * doesn't represent an item-based widget.
 *
 * @param x horizontal coordinate
 * @param y vertical coordinate
 */
public Item scrollDown(int x, int y) {
	return null;
}
/**
 * Scrolls the viewer's control up by one item from the given
 * display-relative coordinates.  Returns the newly revealed Item,
 * or <code>null</code> if no scrolling occurred or if the viewer
 * doesn't represent an item-based widget.
 *
 * @param x horizontal coordinate
 * @param y vertical coordinate
 */
public Item scrollUp(int x, int y) {
	return null;
}
/**