This would be very useful so +1.
"Show on all diagrams" already there, but manual.
"Show links" same, but a second step.
I know people who have mistakenly assumed that if an element does not appear on any diagrams, it must be an orphan, so they mistakenly deleted things from the project browser they didn't really want to delete. Hahaha. Imagine anyone being that careless.
It would help protect the integrity of their models if these dependencies were more easily viewable.