res:dock:: fix tray icons don't update position.

tower:https://tower.im/projects/8f19f0bf0e754f0b82ef2c24bc230973/todos/5d70c05c101b44c1a07ca6ad0eebe0ab/#f58245a12b9f417f97ae4bf2df255182
Change-Id: Icc7388e6b74d395c19036956b3b9f5ea688be5fa