Seems like we can only control the thumbnail photo on springboard screens using the "SetPosterStyle" method on the ifSpringboardScreen interface, with one of these two values:
"rounded-square-generic" – Artwork sizes: SD = 143x129; HD = 209x209 Note: is non-square NTSC pixel aspect ratio images. (Default)
"rounded-rect-16x9-generic" – 16x9 poster style. Artwork Sizes SD=177x90; HD=269x152
Is there anyway to control how the photo is scaled to fit that size, like roPosterScreen does? I would like to use the "scale-to-fit" mode that's available on the poster screens.