Bug 300012 [CommonNavigator] CNF test improvements
Various improvements and corrections.
tests/org.eclipse.ui.tests.navigator/src/org/eclipse/ui/tests/navigator/NavigatorTestBase.java
_commonNavigator.setFocus();
		_viewer = (CommonViewer) _commonNavigator.getAdapter(CommonViewer.class);
	}
	protected void tearDown() throws Exception {
		clearAll();
		
		EditorTestHelper.showView(_navigatorInstanceId, false);
	}
	protected void clearAll() throws Exception {
		IProject[] projects = ResourcesPlugin.getWorkspace().getRoot().getProjects();
		for (int i = 0; i < projects.length; i++) {
			projects[i].delete(true, null);
		}
	}
	protected void refreshViewer() {
		try {
			
			
			
			
			TreeItem[] rootItems = _viewer.getTree().getItems();
			for (int i = 0; i < rootItems.length; i++)
				rootItems[i].setText("");
		} catch (Exception ex) {
			
		}
		_viewer.refresh();
	}
	protected Object verifyMenu(IStructuredSelection sel, String item) {
		MenuManager mm = new MenuManager();