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。在1.5上.
解决方法：
AlertDialog.Builder(xxx.this) => AlertDialog.Builder(this.getParent())