Bug 15586 Warn the user when a project without the Java nature is opened
When opening a closed project that doesn't have the Java nature when opened, then we should inform the user that the opened project will not appear in the packages view.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/ui/actions/OpenProjectAction.java
* 
	 * @param site the site providing context information for this action
	 */
	public OpenProjectAction(IWorkbenchSite site) {
		Assert.isNotNull(site);
		fSite= site;
		setEnabled(hasCloseProjects());
	}
	
	/*
	 * @see IAction#run()
	 */
	public void run() {
		ElementListSelectionDialog dialog= new ElementListSelectionDialog(fSite.getShell(), new JavaElementLabelProvider());
		dialog.setTitle(ActionMessages.getString("OpenProjectAction.dialog.title")); 
		dialog.setMessage(ActionMessages.getString("OpenProjectAction.dialog.message")); 
		dialog.setElements(getClosedProjects());
		dialog.setMultipleSelection(true);
		int result= dialog.open();
		if (result != Dialog.OK)
			return;
		final Object[] projects= dialog.getResult();
		IRunnableWithProgress runnable= new IRunnableWithProgress() {
			public void run(IProgressMonitor monitor) throws InvocationTargetException, InterruptedException {
				monitor.beginTask("", projects.length); 
				MultiStatus errorStatus= null;
				for (int i = 0; i < projects.length; i++) {
					IProject project= (IProject)projects[i];
					try {
						project.open(new SubProgressMonitor(monitor, 1));