Copy as PNG in Present (prototype) mode

I sometimes need to get specific ‘screenshots’ of the UI I’m designing, so I can paste them in a document, for instance. In the canvas I can do Copy as PNG, but the ideal source for such ‘screenshots’ is actually when you run a prototype. Since a prototype can generate a larger number of views dynamically, the result looks more realistic.

I would thus love to see a Copy as PNG equivalent in prototype (“Present”) mode, so I can grab any snapshot of my proto execution. I could of course use an external screen grab tool but I would need to precisely adjust the area to be grabbed, not ideal…