Comment 4 for bug 1107919

> Notify OSD produces fallback alert boxes when applications don't bother to follow the spec
> <https://wiki.ubuntu.com/NotifyOSD#alert>

They don't bother to follow the notify-osd spec because they're not built for notify-osd but for gnome-shell's notifications.

As for using a dialog, it would break the use case Federico mentioned even more (as a system dialog should be modal, or at least always on top) and would break the "i'm dragging something in a drawing program" use case.

You're more than welcome to reopen the original bug if you feel strongly about it. In the meanwhile, I guess that somebody will have to reimplement the gnome-settings-daemon code to match the notify-osd code.