Purchases the next available stable slot, without confirmation. Only available while interacting with a Stable Master NPC (between the PET_STABLE_SHOW and PET_STABLE_CLOSED events and only if IsAtStableMaster() returns true).

Signature:

BuyStableSlot()

This function does not prompt the user for confirmation before its results take effect -- that behavior is provided by the default UI, and this function is called from the confirmation dialog