Chat through bnet is sort of a bother

When someone writes me, the notification of this will not go away unless I answer or I manually remove it in the notification center, reading it is not enough.

When I write someone else I will NOT get a notification if they answer me timely, I dont even know what the window is. But I missed messages a bunch of times now because the other person answered to something I wrote within ~10 minutes and I never got a notification about it.

Why?