A bit of refactoring, added a root fragment to provide future fragment cohesion.  Probably.
Just image if you had a few days to work on a rendering engine and game loop, only cos you were kinda making it up as you went it took a long time to get it into a shape where anything actually worked so you could never form a decent commit, and you were kinda over-reaching from the get-go, so it's a bit over-engineered for what's being asked of it? Well that kinda sorta happened.

You can now select a scan from the scans list and be treated to a quarter of a magenta circle peeking out from the top left of the screen!  BE AMAZED!  THIS IS A SIGN OF...  well, not exactly end times or anything quite so dramatic...