Through refactorings it's easy to loose track of what is not being used anymore. It's also a good way to catch some problem.
I think this is a combination of two ideas (already tackled):http://www.outsystems.com/ideas/2555/unused-variables-actions-or-functions-should-give-a-warning-on-truechange and http://www.outsystems.com/ideas/167/remove-all-unused-references.
Is this right?
I'm happy to announce that your idea is already available on the last release of the OutSystems platform 10.
Thank you for your time and collaboration in making OutSystems platform better.