Looking for an Arduino proto-shield library part that I KNOW exists somewhere

I expect you are looking for this:

https://forums.adafruit.com/viewtopic.php?f=31&t=36560

which at least on Fritzing 0.9.6 produces this:

The reason for the 0.9.6 restriction is that I believe breadboards are always supposed to be on the bottom and not movable, but in 0.9.6 (at least) that doesn’t seen to be true. I can make the breadboard on top. I’m not sure if this is 0.9.6 specific or I misunderstood breadboards.

edit: Learned something new again! The trick here is this part has a breadboard layerId of breadboardbreadboard rather than the standard breadboard. With the layerId set to breadboardbreadboard the part can be moved up and down relative to the breadboard (changing the layerId to breadboard makes it act like a normal part and it won’t go below the breadboard!)

Peter