This new UI system is a lot of work, but in the end I feel that it will be worth it. I've finished fleshing out the drop-down UI type, so that it properly displays and handles both dropped and non-dropped states, as well as interacting with the game when something is selected.
I'm also working on getting star systems to work with the new UI system. I added a new UI type, "CameraView", this will be used for certain types of objects. CameraView supports moving, zooming, etc which isn't implemented yet, but that's the idea. It will be used for galaxy preview as well as space combat.
Here's a screenshot of current version of CameraView (note that galaxy is generated via the new UI!), no shaders, no scaling, no zooming, etc:
What this means is that you can have a galaxy preview inside a screen, maybe planet list screen to show its location, or whatever you think suits your purpose. There's a lot of work to be done still...