-A child watch source will issue an event when the process with the given PID
-dies. To avoid race conditions, it will issue an event even if the process
-dies before the source is created. The callback is called with three
-arguments: the event source, the PID, and the child's exit status.
-
-Note that this source is totally incompatible with any thing that would cause
-perl to change the SIGCHLD handler. If SIGCHLD is changed, under some
-circumstances the module will recognize this circumstance, add a warning to the
-debug log, and continue operating. However, it is impossible to catch all
-possible situations.
-
-=head3 File Descriptor
-
- my $src = Amanda::MainLoop::fd_source($fd, G_IO_IN);
-
-This source will issuen an event whenever one of the given conditions is true
-for the given file descriptor. The conditions are from Glib's GIOCondition,
-and are C<$G_IO_IN>, C<G_IO_OUT>, C<$G_IO_PRI>, C<$G_IO_ERR>, C<$G_IO_HUP>, and
-C<$G_IO_NVAL>. These constants are available with the import tag
-C<:GIOCondition>.
-
-Generally, when reading from a file descriptor, use C<$G_IO_IN|$G_IO_HUP> to
-ensure that an EOF triggers an event as well. Writing to a file descriptor can
-simply use C<$G_IO_OUT>.
-
-=head1 RELATION TO GLIB
-
-Glib's main event loop is described in the Glib manual:
-L<http://library.gnome.org/devel/glib/stable/glib-The-Main-Event-Loop.html>.
-Note that Amanda depends only on the functionality available in Glib-2.2.0, so
-many functions described in that document are not available in Amanda. This
-module provides a much-simplified interface to the glib library, and is not
-intended as a generic wrapper for it. Specifically: