I'm trying to write a confirmation dialog in Ruby/Tk.

I've been able to catch the window destroy event.  However, in the
case where I decide I don't want to exit, how do I stop the event from
propogating and hence causing the window to close?

Of course, this could really be a Tk issue, but I found some Python/Tk
code that says to have the handler return "break", which I've tried
with no success, so I'm guessing there may be something language- or
implementation- dependent about this.

Any ideas?