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/CheckboxTreeViewer.java
checked.add(data);
				if (ti.getGrayed())
					grayed.add(data);
			}
		}
		gatherState(checked, grayed, item);
	}
}
/* (non-Javadoc)
 * Method declared on ICheckable.
 */
public boolean getChecked(Object element) {
	Widget widget = findItem(element);
	if (widget instanceof TreeItem)
		return ((TreeItem) widget).getChecked();
	return false;
}
/**
 * Returns a list of checked elements in this viewer's tree, 
 * including currently hidden ones that are marked as
 * checked but are under a collapsed ancestor.
 * <p>
 * This method is typically used when preserving the interesting
 * state of a viewer; <code>setCheckedElements</code> is used during the restore.
 * </p>
 *
 * @return the array of checked elements
 *
 * @see #setCheckedElements
 */