yeah pretty much, themes you have seen with smaller frames then that just keep the dimensions the same but make the image smaller and just add more shadow shading to the outside, best to have a look at some of the other themes with smaller frames in WSB and see how they do it, you will also see a few themes with no frames on the sides or bottom and again I am pretty sure they just replace those images with the shadow image and also use a tool that removes the blur on explorer frames, I use that myself as I don't like the blur on the frames.