Disable outside PopupWindow, by setFocusable(true)

In the last exercise of "Example of using PopupWindow", user still can touch on views/widgets outside PopupWindow. We can call PopupWindow.setFocusable(true), the PopupWindow will grab the focus from the current focused widget if the popup contains a focusable View. Such that the "Open Popup Window" will be disabled.

package com.exercise.AndroidPopupWindow;

import android.app.Activity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.widget.Button;
import android.widget.PopupWindow;
import android.widget.Toast;

public class AndroidPopupWindowActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        final Button btnOpenPopup = (Button)findViewById(R.id.openpopup);
        btnOpenPopup.setOnClickListener(new Button.OnClickListener(){

   @Override
   public void onClick(View arg0) {
    LayoutInflater layoutInflater 
     = (LayoutInflater)getBaseContext()
      .getSystemService(LAYOUT_INFLATER_SERVICE);  
    View popupView = layoutInflater.inflate(R.layout.popup, null);  
             final PopupWindow popupWindow = new PopupWindow(
               popupView, 
               LayoutParams.WRAP_CONTENT,  
                     LayoutParams.WRAP_CONTENT);  
             
             final Button btnDismiss = (Button)popupView.findViewById(R.id.dismiss);
             btnDismiss.setOnClickListener(new Button.OnClickListener(){

     @Override
     public void onClick(View v) {
      // TODO Auto-generated method stub
      Toast.makeText(AndroidPopupWindowActivity.this, 
        "Dismiss", Toast.LENGTH_LONG).show();
      popupWindow.dismiss();
     }});
               
             popupWindow.showAsDropDown(btnOpenPopup, 50, -30);
             
             //---
             
             popupWindow.setFocusable(true);
             popupWindow.update();
             
             //---
         
   }});
    }
}