NAME
    GPD_SETTRIGGER -- Set the conditions for a game port report

FUNCTION
    This command sets what conditions must be met by a game
    port unit before a pending Read request will be satisfied.
    These conditions, called triggers, are independent -- that
    any one occurs is sufficient to queue a game port report to
    the Read queue.  These conditions are inquired with
    AskTrigger.

    This command always executes immediately.

IO REQUEST
    io_Message      mn_ReplyPort set if quick I/O is not possible
    io_Device       preset by the call to opendevice
    io_Unit         preset by the call to opendevice
    io_Command      GPD_SETTRIGGER
    io_Flags        IOB_QUICK set if quick I/O is possible
    io_Length       sizeof(gamePortTrigger)
    io_Data         a structure of type gameporttrigger, which
                    has the following elements
        gpt_Keys -
                GPTB_DOWNKEYS set if button down transitions
                trigger a report, and GPTB_UPKEYS set if button up
                transitions trigger a report
        gpt_Timeout -
                a time which, if exceeded, triggers a report;
                measured in vertical blank units (60/sec)
        gpt_XDelta  -
                a distance in x which, if exceeded, triggers a
                report
        gpt_YDelta  -
                a distance in x which, if exceeded, triggers a
                report