How to make ForceScheduler show available branches in drop-down list ?

I'm using a **ForceScheduler** to allow users to schedule builds using a button from our local buildbot webpage.

I would like the UI to show a drop-down list with the available branches for a particular repository. This way users don't have to type their feature branch names correctly each time. How do I achieve that ?

So far I've looked at exploiting the **codebases** option of **ForceScheduler** (see example http://docs.buildbot.net/current/manual/configuration/schedulers.html#forcescheduler-scheduler) - but the **branch** choices are hardcoded in all the examples I've seen. I'd like to avoid updating the buildbot config whenever a users pushes a new branch in the tracked repos.