How can I adjust "raytraced preview" iterations from 20 to higher numbers ?

[MentalRayUser]

I see only number getting higher from 0 to 20
look over preferences tab , but without success 

and one more question please , do you plan to implement GPU acceleration ?
I know you have your own CPU renderfarm that can't stay without work , but anyway ...
there is a lacking of performance a little bit .

[Oshyan]

You cannot adjust the number of iterations at this time. It has a fixed maximum so that it does not "calculate forever". We may allow adjustment in the future.

A GPU version of the RTP is a possibility in the future. GPU acceleration for *primary* rendering is not likely to happen soon, however.

- Oshyan