If you attach an existing image to your encounters, the paint screen comes up when you click on it .. but currently, although you can draw on the image, you can not save the drawings. You can only save drawings from within the results tab, or using the paint screen within the encounter editor. I'll look to see how difficult it is to enable saving ...
I have thought about this again, and if these are results etc .. perhaps inking onto these again should not be allowed.