[Libreoffice] Notifications between different SfxObjectShells

Hey,

I'm trying to improve calc's copy behavior but I'm a bit stuck with
the last step. I need to get a notification if another document is
being saved because I may need to adjust the reference to this
document. I found already SfxEventHint which broadcasts all relevant
information but only to the same SfxObjectShell while I need it in
another shell.

I can even write a SfxListener and register it in the other
SfxObjectShell if that helps. Is there already a solution for such
situations or do I need to write something myself?

Thanks,
Markus