I think I am correct in saying DOpus does not, at the moment, support the display of a dismissable dialogue box, to display a user-defined message.
This came to mind when I was using one of Ken Alcock's buttons ( [Diff/Merge Toolbar) ), which took a fairly lengthy time to finish, and when it did, it was not at all obvious that it had.
It struck me it would be useful to be able to have DOpus display a dialogue box to say the job was done.
You can use @confirm.
@confirm The task has completed!|ThanksAh, OK. Thanks Steve.
Regards...
Bernard
That button can take awhile in a folder listing many files (but it is still quicker for simple comparison than the Synchronize Panel). I scripted it for Opus 8, and the @confirm modifier didn't exist.
I'm working on modernizing and streamlining my buttons using Opus 9 techniques. I'll make sure that one gets a confirm dialog (or at least a confirmation bell from your PC speaker).
"modernizing" and "bell from your PC speaker" do not belong in the same paragraph imo. 
It is, after all, 2007 not 1985.
Tell me how to make it play Rock-N-Roll and I will! 
Hello Ken...
I guessed that was the case.
I’d vote for @confirm. If you want to make a sound at the same time, why not one of the DOpus .WAV files? Most users have speakers these days.
Regards...
Bernard