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
} else if (MembersOrderPreferenceCache.isMemberOrderProperty(event.getProperty())) {
			refreshViewer= true;
		}
		if (refreshViewer)
			fViewer.refresh();
	}
	
	/* (non-Javadoc)
	 * @see IViewPartInputProvider#getViewPartInput()
	 */
	public Object getViewPartInput() {
		if (fViewer != null) {
			return fViewer.getInput();
		}
		return null;
	}
	public void collapseAll() {
		try {
			fViewer.getControl().setRedraw(false);		
			fViewer.collapseToLevel(getViewPartInput(), AbstractTreeViewer.ALL_LEVELS);
		} finally {
			fViewer.getControl().setRedraw(true);
		}
	}
	
	public PackageExplorerPart() { 
		initLinkingEnabled();
		fSelectionListener= new ISelectionChangedListener() {
			public void selectionChanged(SelectionChangedEvent event) {
				handleSelectionChanged(event);