F17: How to always show desktop notifications?

[sguazt]

Hello,

In GNOME, when you have "unread" desktop notifications come from a
specific source (e.g., empathy, mail-notification), all new
notifications from that source do not pop-up.
Instead, they are stacked up in the "unread notifications" place
(which appears as the envelope-like icon the systray area).

I don't like this. I just want every notification to pop-up (even if
there are already ones, coming from the same source, to be read) and
eventually to go in the "unread notifications" place.

Is there a way to get this?

Note, I don't use GNOME Shell. I use OpenBox as Window Manager
together with GNOME apps (gnome-settings-daemon,
notification-daemon,...)

Thank you very much!

Best,

-- Marco