This class is part of the Gallery family. This class implements the
AEEIID_IGalleryNotifier interface and provides the user notifications when
a Gallery is available for writing. This serves as an indication to the
user that the Gallery may be available for writing. If writing to the
Gallery fails, the user should wait for the next time the registerd
is fired and should try again. This allows multiple clients to
be waiting to write to the Gallery and for them to schedule themselves in
round-robin style to run when another has finished.