How to render a region of the viewport?

[Micha]

Hi,

a long time I avoided the often used function, since it doesn't work anymore and last I read somewhere it could work again ... but I don't get it. I would like to define a region at the viewport and this region is rendered at the VFB at the right place. How can this be done? If it doesn't work, could it be added again please?

-Micha