res:dock:: fix menu problem.

tower:https://tower.im/projects/8f19f0bf0e754f0b82ef2c24bc230973/todos/df692ee5058343f9a834157662277bfe/
Change-Id: I6d3faa63df22b502ed01a57e697850747ab79f0b
res:dock:: fix preview window problem.

tower:https://tower.im/projects/8f19f0bf0e754f0b82ef2c24bc230973/todos/12107008efb64dac92f90dbb03fc37a7/
Change-Id: I89a0ea59b04db23b6fdb1eb34dff096985610b79