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/AbstractTreeViewer.java
}
	return null;
}
/**
 * Sets the auto-expand level.
 * The value 0 means that the root's children are not visible; 
 * 1 means that the root is expanded so that its children are visible,
 * but the root's grandchildren are not; and so on.
 * The value <code>EXPAND_ALL</code> means that all subtrees should be
 * expanded.
 *
 * @param level non-negative level, or <code>EXPAND_ALL</code> to expand
 *  all levels of the tree
 */
public void setAutoExpandLevel(int level) {
	expandToLevel = level;
}
/**
 * The <code>AbstractTreeViewer</code> implementation of this method
 * checks to ensure that the content provider is an <code>ITreeContentProvider</code>.
 */
public void setContentProvider(IContentProvider provider) {
	Assert.isTrue(provider instanceof ITreeContentProvider);
	super.setContentProvider(provider);
}
/**
 * Sets the expand state of the given item.
 *
 * @param item the item
 * @param expand the expand state of the item