I just started building a small RubyTk application, created a TkRoot object, and added an event callback for the "Destroy" event.
root=TkRoot.new({'title'=>"Some Name"})
root.bind("Destroy", proc {puts "Goodbye, cruel world!"})
When I click the little 'X' in the corner, "Goodbye, cruel world!" is echoed twice.
How can I make the callback function be invoked only once?