res:launcher:: fix keyboard scroll problem.

the category indicator is not changed when category list is scrolled
with keyboard.

tower: https://tower.im/projects/8f19f0bf0e754f0b82ef2c24bc230973/todos/cd53a497116d47e9883f2fa221999628/

Change-Id: Ibc6c8a8adfa8e60c900f51b7c4bfd327eb9fbc42