The signal accumulator is a special callback function that can be used
to collect return values of the various callbacks that are called
during a signal emission. The signal accumulator is specified at signal
creation time, if it is left %NULL, no accumulation of callback return
values is performed. The return value of signal emissions is then the
value returned by the last callback.
The accumulator function returns whether the signal emission
should be aborted. Returning %FALSE means to abort the
current emission and %TRUE is returned for continuation.
The signal accumulator is a special callback function that can be used to collect return values of the various callbacks that are called during a signal emission. The signal accumulator is specified at signal creation time, if it is left %NULL, no accumulation of callback return values is performed. The return value of signal emissions is then the value returned by the last callback.