dock-applets: fix notification area settings

tower: https://tower.im/projects/8f19f0bf0e754f0b82ef2c24bc230973/todos/62571aaaebfa4d539b75aae6d7f59cd8/
tower: https://tower.im/projects/8f19f0bf0e754f0b82ef2c24bc230973/todos/3857841dc9514a0cbf9a3dcd11c7bad2/

Change-Id: I398b6527478bccd78b00fd3426031aee842f5bfd