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
void projectStateChanged(Object root) {
		Control ctrl= fViewer.getControl();
		if (ctrl != null && !ctrl.isDisposed()) {
			fViewer.refresh(root, true);
			
			
			fViewer.setSelection(fViewer.getSelection());
		}
	}
    public boolean tryToReveal(Object element) {
		if (revealElementOrParent(element))
            return true;
        
        WorkingSetFilterActionGroup workingSetGroup= fActionSet.getWorkingSetActionGroup().getFilterGroup();
        if (workingSetGroup != null) {
		    IWorkingSet workingSet= workingSetGroup.getWorkingSet();  	    
		    if (workingSetGroup.isFiltered(getVisibleParent(element), element)) {
		        String message= PackagesMessages.getFormattedString("PackageExplorer.notFound", workingSet.getName());  
		        if (MessageDialog.openQuestion(getSite().getShell(), PackagesMessages.getString("PackageExplorer.filteredDialog.title"), message)) { 
		            workingSetGroup.setWorkingSet(null, true);		
		            if (revealElementOrParent(element))
		                return true;
		        }
		    }
        }
        
        CustomFiltersActionGroup filterGroup= fActionSet.getCustomFilterActionGroup();
        String[] filters= filterGroup.removeFiltersFor(getVisibleParent(element), element, getTreeViewer().getContentProvider()); 
        if (filters.length > 0) {