maximum priority source to check
location to store timeout to be used in polling
location to store #GPollFD records that need to be polled.
the number of records actually stored in @fds, or, if more than @n_fds records need to be stored, the number of records that need to be stored.
Determines information necessary to poll this main loop. You should be careful to pass the resulting @fds array and its length @n_fds as is when calling g_main_context_check(), as this function relies on assumptions made when the array is filled.
You must have successfully acquired the context with g_main_context_acquire() before you may call this function.