Unable to add window is not valid; is your activity running?

郁闷的Bug，终于解决了，分享一下解决方案！

错误:
android.view.WindowManager$BadTokenException: Unable to add window -- token android.app.LocalActivityManager$LocalActivityRecord@435def20 is not valid; is your activity running? at android.view.ViewRoot.setView......

发生环境：
在一个tabActivity里面嵌套一个tabAcitivity, 如果在子tabActivity里面显示AlertDialog的话，就会引发此错误。

解决方法：
AlertDialog.Builder(xxx.this) => AlertDialog.Builder(this.getParent())

文章引用自：http://macleo.iteye.com/blog/1486684