Bug 30341 NPE attempting "Show in package explorer" [packge explorer]
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/PackageExplorerPart.java
}
		});
		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)
			 */
			protected Object[] getFilteredChildren(Object parent) {
				List list = new ArrayList();
				ViewerFilter[] filters = fViewer.getFilters();