process-wait-for-event &key wait-reason wait-function process-other-messages-p no-hang-p stop-at-user-operation-p => event
The function process-wait-for-event
calls mailbox-wait-for-event on the mailbox of the current process, after ensuring that the current process has a mailbox.
The arguments and value are interpreted as for mailbox-wait-for-event.
LispWorks User Guide and Reference Manual - 20 Sep 2017