The comment feature could be separated in 2 different functions.
It is mandatory to be able to communicate with colleagues about specific changes that should be made on a mock.
It would also be good to be able to detail the flow or the way a UI pattern works.
Keeping them separated would allow designers to hide or complete a comment made by someone else and keep the details / specs to stick to the mocks.
Being able to switch between the comments and the details would help the designer to select what he wants to read.
