Bug 81877 Package explorer forgets active working set [package explorer]
3.1 M4 1. open pkg explorer. 2. select a working set, pkg explorer updates and filters out projects. 3. close pkg explorer. 4. open package explorer again and the working set is no longer applied. This used to work.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/PackageExplorerPart.java
Object element= iter.next();
				TreePath[] pathsToRestore= toRestore.getTreePaths(element);
				CustomHashtable currentParents= createRootAccessedMap(contentProvider.getTreePaths(element));
				for (int i= 0; i < pathsToRestore.length; i++) {
					TreePath path= pathsToRestore[i];
					Object root= path.getFirstSegment();
					if (root != null && path.equals((TreePath)currentParents.get(root), getComparer())) {
						pathsToSelect.add(path);
					}
				}
			}
			List toSelect= new ArrayList();
			for (Iterator iter= pathsToSelect.iterator(); iter.hasNext();) {
				TreePath path= (TreePath)iter.next();
				int size= path.getSegmentCount();
				if (size == 0)
					continue;
				Widget current= getTree();
				int last= size - 1;
				Object segment;
				for (int i= 0; i < size && current != null && (segment= path.getSegment(i)) != null; i++) {
					internalExpandToLevel(current, 1);
					current= internalFindChild(current, segment);
					if (i == last && current != null)
						toSelect.add(current);
				}
			}
			getTree().setSelection((TreeItem[])toSelect.toArray(new TreeItem[toSelect.size()]));
		}
	    private Widget internalFindChild(Widget parent, Object element) {