Feature request: PageMediaSelect sourcing media from all pages

I was trying to write a page blueprint where I would be able to reference media from another page through a PageMediaSelector control. It seems this isn't possible, though.

I think adding an option for this would be very useful. My scenario - which isn't an edge case or anything - is one where I want to stitch together a home page from images that belong to other pages, without duplicating those image files.

I saw that this idea had previously been brought up in #605, but that ticket was more of a support request, and it seems like the feature might not have been really considered.