The other day I was cleaning my (new to me) P, and was surprised how it does parallax correction. The eyepiece has a glass cover. When you remove it you see the real viewfinder with framelines etched into it. When doing parallax correction, the entire finder is moved.
New to me, coming from Leica land where only a frame mask is moved ....
No answer to the OP's question, just thought it was worth mentioning.
Cheers,
Roland.