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
if (expandedElements.length > 0) {
			IMemento expandedMem= memento.createChild(TAG_EXPANDED);
			for (int i= 0; i < expandedElements.length; i++) {
				IMemento elementMem= expandedMem.createChild(TAG_ELEMENT);
				
				Object o= expandedElements[i];
				if (o instanceof IJavaElement)
					elementMem.putString(TAG_PATH, ((IJavaElement) expandedElements[i]).getHandleIdentifier());
			}
		}
	}
	private void restoreFilterAndSorter() {
		fViewer.addFilter(new OutputFolderFilter());
		setSorter();
		if (fMemento != null)	
			fActionSet.restoreFilterAndSorterState(fMemento);
	}
	private void restoreUIState(IMemento memento) {
		
		restoreCurrentFrame(memento);
		
		
		
		
	}
	private void restoreCurrentFrame(IMemento memento) {
		IMemento frameMemento = memento.getChild(TAG_CURRENT_FRAME);
		
		if (frameMemento != null) {
	        FrameAction action = fActionSet.getUpAction();