RCP如何将视图的右键进行隐藏显示

package myviewrcp2;

import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.action.Action;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.ui.ISelectionListener;
import org.eclipse.ui.IWorkbenchPart;
import org.eclipse.ui.IWorkbenchWindow;
import org.eclipse.ui.actions.ActionFactory.IWorkbenchAction;

public class MyAction extends Action implements ISelectionListener,IWorkbenchAction{

	private IWorkbenchWindow window;
	public final static String ID = "myviewrcp2.MyAction";
	
	public MyAction(IWorkbenchWindow window) {
		super("Test Action");
		setId(ID);
		setText("MyAction");
		setToolTipText("My Action");
		this.window = window;
		//注册选择服务监听器
		window.getSelectionService().addSelectionListener(this);
	}
	
	public void run() {}
	
	//IWorkbenchAction 接口中的方法，释放后取消注册
	@Override
	public void dispose() {
		// TODO Auto-generated method stub
		window.getSelectionService().removeSelectionListener(this);
	}

	//接口 ISelectionListener 中的方法
	@Override
	public void selectionChanged(IWorkbenchPart part, ISelection incoming) {
		// TODO Auto-generated method stub
		if(incoming instanceof IStructuredSelection) {
			//获得事件发生的源所携带的对象
			IStructuredSelection selection = (IStructuredSelection) incoming;
			String s = (String) selection.getFirstElement();
			if(s == null || "".equals(s)) {
				return;
			}
			//如果选择的是Three，则设置为可用，否则设置为不可用
			if(s.equals("Three3")) {
				setEnabled(true);
			}else {
				setEnabled(false);
			}
		}
	}

	
}