Bug 31683 Show In doesn't work for class file in rt.jar
I20030611 - create Test project that uses Jar container - open NumberFormat.class - activate Show In... and choose Package Explorer Observe: NumberFormat.class doesn't get revealed.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/PackageExplorerActionGroup.java
fMemberFilterActionGroup.contributeToViewMenu(menu);
		}
		menu.add(fToggleLinkingAction);
		menu.add(new Separator(IWorkbenchActionConstants.MB_ADDITIONS));
		menu.add(new Separator(IWorkbenchActionConstants.MB_ADDITIONS+"-end"));		
	}
	 void handleSelectionChanged(SelectionChangedEvent event) {
		fZoomInAction.update();
	}
	
	public void fillContextMenu(IMenuManager menu) {		
		IStructuredSelection selection= (IStructuredSelection)getContext().getSelection();
		int size= selection.size();
		Object element= selection.getFirstElement();
		
		addGotoMenu(menu, element, size);
		
		addOpenNewWindowAction(menu, element);
		
		super.fillContextMenu(menu);
	}
	
	 private void addGotoMenu(IMenuManager menu, Object element, int size) {
		
		if (size == 1 && fPart.getViewer().isExpandable(element) && (isGoIntoTarget(element) || element instanceof IContainer))
			menu.appendToGroup(IContextMenuConstants.GROUP_GOTO, fZoomInAction);
	}
	
	private boolean isGoIntoTarget(Object element) {
		if (element == null)