If none is suitable for your case, you can write your own. Writing a custom dialog is relatively easy. You can put anything you like into it.
Am I right in thinking that, leaving aside the system provided printer dialog(u)es etc., a dialogue or messagebox is really just a custom form with no special magic?
I've occasionally considered doing my own warning/note boxes that have a timeout and prioritisation: in my case most of this sort of thing is logged and results in an audible warning, and it can be inconvenient to come back and find that there's a hundred low-priority warnings to be cleared off the screen before something more important can be done.
MarkMLl