Possible to lock IPR size to render size?

[fixeighted]

As in the title, is this possible to do? - I can't see an option but would be good as a toggle.

Why? So I don't have to get annoyed trying to fix stuff like this, for example.
EG 1 is IPR and is what I want.
EG 2 is the full size which is crap and so utterly different to the IPR that it is truly frustrating (usual difference in bump size)
The full is 4k across and the IPR is an arbtrary size...here half that size.
If I could lock it I could adjust more easily

[fixeighted]

I can see that with the beta 5 VFB this is now possible, so that's great.
However I notice that the presets are logical apart from the fact that it goes 50%, 75% and then 110%.
Can I assume this is an error and it should in fact be 100% ?