Notifications should not disappear after checking

Notifications should not disappear after checking. If a user logout or close the page the notification disappear. 

i don't know why i can't edit this post :/ I checked it again..I think notifications disappear after some time, not by closing browser or logging out. But still they shouldn't disappear.

Only not viewed notifications are shown here, you still can view all notifications on the separate notification page (click on "notification" title).