set-breakables in drscheme:unit:tab<%>
Calling this method with a thread and a custodian means that the next time the break button is clicked, it will either break the thread or shutdown the custodian.
See also
get-breakables.
(-> voidsenda-drscheme:unit:tabset-breakablesthreadcustodian)
thread: (union thread #f)
custodian: (union custodian #f)