If storeToRecoveryFile
has not been called before, this method returns whether the document
has been modified since it has been loaded respectively created.
When saving a session, either in case of an emergency (when OpenOffice.org crashed), or during a
periodic session save as configured by the user, storeToRecoveryFile() is called for every
document where wasModifiedSinceLastSave
returns `TRUE`.
It's allowed to implement this method sloppy, by returning `TRUE` in cases where it is not sure whether
the document actually has been modified. So, the most simple implementation could simply delegate this call
to com::sun::star::util::XModifiable::isModified(). (Well, actually that's the
second simple implementation, the most simple one would, still legitimately, always return `TRUE`.)
However, in such a case, the document might be saved more often than needed. In particular during the
periodic session save, this might become a problem when saving is expensive, for a single document
or the sum of all open documents.