Bug 32656 Open/Close project in package explorer looses selection on java-projects. [package explorer]
Not on non-java projects, which looks wrong when multiple java- and non-java-projects are opened/closed.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/PackageExplorerPart.java
fViewer.addOpenListener(new IOpenListener() {
			public void open(OpenEvent event) {
				fActionSet.handleOpen(event);
			}
		});
		IStatusLineManager slManager= getViewSite().getActionBars().getStatusLineManager();
		fViewer.addSelectionChangedListener(new StatusBarUpdater(slManager));
		fViewer.addTreeListener(fExpansionListener);
	
		if (fMemento != null)
			restoreUIState(fMemento);
		fMemento= null;
	
		 
		JavaUIHelp.setHelp(fViewer, IJavaHelpContextIds.PACKAGES_VIEW);
		
		fillActionBars();
		updateTitle();
	}
	/**
	 * This viewer ensures that non-leaves in the hierarchical
	 * layout are not removed by any filters.
	 * 
	 * @since 2.1
	 */
	private ProblemTreeViewer createViewer(Composite parent) {
		return  new ProblemTreeViewer(parent, SWT.MULTI | SWT.H_SCROLL | SWT.V_SCROLL) {
			/*
			 * @see org.eclipse.jface.viewers.StructuredViewer#filter(java.lang.Object)
			 */