#i124970# fix DocumentFocusListener::notifyEvent's handling of IndexOutOfBoundsException

the DocumentFocusListener::notifyEvent() throw list only allows a RuntimeException to
propagate. The methods called in notifyEvent() allow IndexOutOfBoundsException though,
so it must be handled in all cases to prevent C++ from invoking its unexpected() abort
mechanisms. Ceterum censeo, non-empty throw lists should be removed altogether...