Bug 81426 Package Explorer shows nothing after drill into working set, then show projects
I200412160800 - switch Package Explorer to working sets - context menu > Go Into a working set - Show > Projects -> view is empty -> view toolbar button 'Up to Working Sets' does not do anything
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/PackageExplorerPart.java
* to add your own context dependent menu contributions.
	 */
	public void menuAboutToShow(IMenuManager menu) {
		JavaPlugin.createStandardGroups(menu);
		
		fActionSet.setContext(new ActionContext(getSelection()));
		fActionSet.fillContextMenu(menu);
		fActionSet.setContext(null);
	}
	private void makeActions() {
		fActionSet= new PackageExplorerActionGroup(this);
		if (fWorkingSetModel != null)
			fActionSet.getWorkingSetActionGroup().setWorkingSetModel(fWorkingSetModel);
	}
	
	
	
	private void initDragAndDrop() {
		initDrag();
		initDrop();
	}
	private void initDrag() {
		int ops= DND.DROP_COPY | DND.DROP_MOVE | DND.DROP_LINK;
		Transfer[] transfers= new Transfer[] {
			LocalSelectionTransfer.getInstance(), 
			ResourceTransfer.getInstance(),
			FileTransfer.getInstance()};
		TransferDragSourceListener[] dragListeners= new TransferDragSourceListener[] {
			new SelectionTransferDragAdapter(fViewer),
			new ResourceTransferDragAdapter(fViewer),