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       giiEventPoll,  giiEventSelect, giiEventsQueued, giiEventRead - Wait for
       and receive events


       #include <ggi/gii.h>

       gii_event_mask giiEventPoll(gii_input_t inp, gii_event_mask mask,
                                   struct timeval *t);

       int giiEventSelect(gii_input_t inp, gii_event_mask *mask, int n,
                          fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
                          struct timeval *timeout);

       int giiEventsQueued(gii_input_t inp, gii_event_mask mask);

       int giiEventRead(gii_input_t inp, gii_event *ev, gii_event_mask mask);


       giiEventPoll waits for specific events to become available on an input.
       This  call  somewhat  resembles  the  Unix select(2) call, but only for
       LibGII events and is more portable.   The  function  returns  after  an
       event matching the given event mask is available or after the amount of
       time specified by t has elapsed, whichever occurs first.  If t is NULL,
       there is no timeout.

       The timeout value on return is updated to the time that would have been
       remaining.  So  make  sure  to  re-setup  this   value   when   calling
       giiEventPoll in a loop.

       giiEventSelect   is  the  combination  of  giiEventPoll  and  select(2)
       allowing to wait for both LibGII events and arbitrary file  descriptors
       in any of the three states.  However, this function is not available if
       the operating system does not support the select(2) call, not even as a

       giiEventsQueued  returns  the  number  of events matching the specified
       event mask that are currently queued in the input.

       giiEventRead blocks for and transfers an event from the given input  to
       the  location  pointed  to by ev. The event with the earliest timestamp
       that matches the given mask is returned to the application.


       giiEventPoll returns a mask of available  events  (constrained  by  the
       given  mask).   It  is  0  if  no  events  are available.  On error, an
       negative gii-error(3) code is returned.

       giiEventSelect returns the same  values  as  select(2).   Unlike  other
       LibGGI/LibGII functions, it also uses errno. It will update the timeout
       regardless of whether or not the system call does so.

       giiEventsQueued returns the number of events.

       giiEventRead returns the size of event on success, and 0 on error.


       This is one of the various ways of coding an event-polling loop:

       for(;;) {
           tv.tv_sec = 0;
           tv.tv_usec = 100; /* change to 0 for non-blocking behaviour */

           ggiEventPoll(vis, emAll, &tv);
           n = ggiEventsQueued(vis, emAll);

           /* Process events in one gulp, when available */
           while(n--) {
               ggiEventRead(vis, &ggievent, emAll);
               switch(ggievent.any.type) {
                   /* ... */

           /* Do other stuff */

              Note: This code uses the LibGGI functions and types  instead  of
              the LibGII ones, since the former is the more common case.