I imagine it would also depend on the event. If there was a cover charge and all other alcoholic drinks were sold, I'm sure you could give away your homebrew. However, if the cover charged allows people to get their alcohol free, then it would be illegal, because you would be selling homebrew.
You will have to several people in Alcohol control unit, and you might find one or two that will say yes. Last year, a club in Midland wanted to pour their beers at a fundraiser with a cover charge and free drinks. Texas Alcoholic Beveage Commission Agent told them it was illegal to transport home brew (It's not, and they told her so.), and said they didn't have the proper permits to sell alcohol anyway.