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
} 
		
	 public void dispose() {
		if (fContextMenu != null && !fContextMenu.isDisposed())
			fContextMenu.dispose();
		getSite().getPage().removePartListener(fPartListener);
		JavaPlugin.getDefault().getPreferenceStore().removePropertyChangeListener(this);
		if (fViewer != null)
			fViewer.removeTreeListener(fExpansionListener);
		
		if (fActionSet != null)	
			fActionSet.dispose();
		if (fFilterUpdater != null)
			ResourcesPlugin.getWorkspace().removeResourceChangeListener(fFilterUpdater);
		if (fWorkingSetModel != null)
			fWorkingSetModel.dispose();
		super.dispose();	
	}
	/**
	 * Implementation of IWorkbenchPart.createPartControl(Composite)
	 */
	public void createPartControl(Composite parent) {
		
		fViewer= createViewer(parent);
		fViewer.setUseHashlookup(true);
		
		initDragAndDrop();
		
		setProviders();