Option to dismiss time controlled info banners

[cdipe]

The time control of info banners is very useful for administrators.
But when having seen the banner, or the information does not concern the user, it gets annoying and takes up space.

Suggestion:
Keep the alternative to dismiss the banner also when it is time controlled.
(I'm not sure if the option to reset visibility is needed in this case, but since it already exists, why not?)