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
return null;
			return result;
		}
		protected Widget internalGetWidgetToSelect(Object element) {
			Widget result= findItem(element);
			if (!(result instanceof TreeItem))
				return result;
			if (isInHistroyWorkingSet((TreeItem)result)) {
				List l= (List)fAdditionalMappings.get(element);
				if (l != null && !l.isEmpty()) {
					return (Widget)l.get(0);
				} else {
					
					
					return null;
				}
			}
			return result;
		}
		private boolean isInHistroyWorkingSet(TreeItem item) {
			TreeItem parent= item.getParentItem();
			while (parent != null) {
				Object data= getElement(parent);
				if (data instanceof IWorkingSet && HistoryWorkingSetUpdater.ID.equals(((IWorkingSet)data).getId()))
					return true;
				parent= parent.getParentItem();
			}
			return false;
		}
	    protected boolean isSameSelection(List items, Item[] current) {