dock:: fix switch window problem.

open multi-window of one app like gedit, the windows that belong to the
app cannot be switched by clicking he item on dock.

reason:
the app.state is not update currently.

tower: https://tower.im/projects/1c0cd0c59ef941298c6e6b2ba6833b91/todos/c5becf8ae90043ba9e81e45b5b1758c7/

Change-Id: I3c4391a27f8567f2e5b0fadc591b364806d8df58