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
* When selection linking with the editor is enabled the view selection tracks
 * the active editor page. Similarly when a resource is selected in the packages
 * view the corresponding editor is activated. 
 */
 
public class PackageExplorerPart extends ViewPart  
	implements ISetSelectionTarget, IMenuListener,
		IShowInTarget,
		IPackagesViewPart,  IPropertyChangeListener, 
		IViewPartInputProvider {
	
	private static final String PERF_CREATE_PART_CONTROL= "org.eclipse.jdt.ui/perf/explorer/createPartControl"; 
	private static final String PERF_MAKE_ACTIONS= "org.eclipse.jdt.ui/perf/explorer/makeActions"; 
	
	private boolean fIsCurrentLayoutFlat; 
	private static final int HIERARCHICAL_LAYOUT= 0x1;
	private static final int FLAT_LAYOUT= 0x2;
	
	public final static String VIEW_ID= JavaUI.ID_PACKAGES;
				
	
	static final String TAG_SELECTION= "selection"; 
	static final String TAG_EXPANDED= "expanded"; 
	static final String TAG_ELEMENT= "element"; 
	static final String TAG_PATH= "path"; 
	static final String TAG_VERTICAL_POSITION= "verticalPosition"; 
	static final String TAG_HORIZONTAL_POSITION= "horizontalPosition"; 
	static final String TAG_FILTERS = "filters"; 
	static final String TAG_FILTER = "filter"; 
	static final String TAG_LAYOUT= "layout";