Bug 167323 [Viewers]Open AbstractTreeViewer for external widget implementors
As reported by Ross Camara AbstractTreeViewer would work for nebula if we would open the API a bit. Boris and I decided that we will do this in 2 steps: 1. open the API 2. moving the Virtual-Support bits from TreeViewer to AbstractTreeViewer when the nebula grid provides virtual support.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
setSelectionToWidget(Arrays.asList(treeSelection.getPaths()),
					reveal);
		} else {
			super.setSelectionToWidget(selection, reveal);
		}
	}
	/**
	 * 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);
			}