Render History + Compare

[DeckB]

I can't seem to find the render history toggle in Frame Buffer. Ultimately what I'm trying to do is render a scene twice with varying adjustments, then compare the output in Frame Buffer (looks like this may be possible via s slider tool).

Thanks.

OSX
SU 2018
Vray 3.6

[DeckB]

I've found the history toggle, so please disregard.