The Scene Graph application will scale the design elements and the graphical images for the actual supported resolution, but you can achieve the best appearance for all supported resolutions if you provide both resolutions of graphical images.
I wrote to manifest-file
and set all coordinates as if I had Roku-device with FullHD, and I got wrong layout, nothing was scaled to my 720p on roku stick. It doesn't work in both way. I have set translations, widths and heights for 720p and "ui_resolutions=FHD,HD", then put it to roku 4 with FHD, and it wasn't scaled, I know it because