Bug 91409 Project Open/Close items are disabled when Package Explorer active
Project Open/Close option in the Project menu is disabled in Plugin prespective.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/workingsets/WorkingSetActionGroup.java
private static final String GROUP_WORKINGSETS= "group.workingSets"; 
	
	private IViewSite fSite;
	private ISelectionChangedListener fLazyInitializer= new  ISelectionChangedListener() {
		public void selectionChanged(SelectionChangedEvent event) {
			ISelectionProvider selectionProvider= fSite.getSelectionProvider();
			IActionBars actionBars= fSite.getActionBars();
			selectionProvider.removeSelectionChangedListener(fLazyInitializer);
			ISelection selection= event.getSelection();
			
			fRemoveAction= new RemoveWorkingSetElementAction(fSite);