quote : "Hmm, but does it crash, or is it saving the PNG file without the frame number?"
as for pngs, they crash the app, but exr don't.
Read my 2 previous posts, the case is resolved
i'm sorry i wrote a lot and keeping being track of where i am (in my investigations) is a bit confusing
but this post with those numerous replies kept me being aware of what i've done and what i had tried so far, what works and what's not.
Thanks a lot for your feedbacks JuanJgon,
given all your work in all those renderers and apps, it's good to have an eye on our problems.