Counter callback, informs the progress of the operation to the client. \n
* Text contains a constant string that is NULL during normal counting, a title in the begining of a sequence
* and a message in the begining of a count.
* Counter id identifies diferrent counters. \n
* Progress in a count reports a value from 0 to 1000.
* If -1 indicates the start of a sequence of operations, 1001 ends the sequence. \n
* If returns 0 the client should abort the operation. \n
* If the counter is aborted, the callback will be called one last time at 1001.
* \ingroup counter
Counter callback, informs the progress of the operation to the client. \n * Text contains a constant string that is NULL during normal counting, a title in the begining of a sequence * and a message in the begining of a count. * Counter id identifies diferrent counters. \n * Progress in a count reports a value from 0 to 1000. * If -1 indicates the start of a sequence of operations, 1001 ends the sequence. \n * If returns 0 the client should abort the operation. \n * If the counter is aborted, the callback will be called one last time at 1001. * \ingroup counter