Bug 161086 [Viewers] performance problem in AbstractTreeViewer.internalExpandToLevel
If you expand to ALL_LEVELS, internalExpandToLevel will call createChildren even if the element has no children, i.e. it does not check if the element is expandable. Found this while experimenting with the Quick Access feature (enter "con", then delete all three characters one at a time).
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
}
	}
	/**
	 * Returns a list of tree paths corresponding to expanded nodes in this
	 * viewer's tree, including currently hidden ones that are marked as
	 * expanded but are under a collapsed ancestor.
	 * <p>
	 * This method is typically used when preserving the interesting state of a
	 * viewer; <code>setExpandedElements</code> is used during the restore.
	 * </p>
	 * 
	 * @return the array of expanded tree paths
	 * @see #setExpandedElements
	 * 
	 * @since 3.2
	 */
	public TreePath[] getExpandedTreePaths() {
		ArrayList items = new ArrayList();
		internalCollectExpandedItems(items, getControl());
		ArrayList result = new ArrayList(items.size());
		for (Iterator it = items.iterator(); it.hasNext();) {
			Item item = (Item) it.next();
			TreePath treePath = getTreePathFromItem(item);
			if (treePath != null) {
				result.add(treePath);
			}
		}
		return (TreePath[]) result.toArray(new TreePath[items.size()]);
	}
	private boolean isTreePathContentProvider() {