Thoughts
So right now the prompt in SMASH is locked to the bottom of the screen, but I think I only want it locked to the bottom when you have
scrollback below it. If you have scrollback above and below it, it locks to the bottom.
This is weird because how scrolling works is also weird. I think we allow scroll-past-end, and we do auto-scrolling—the big one is that if you enter a command, that input command won't scroll past the top of the screen.
If you scroll-past-end, like when you first open a traditional terminal, the prompt is at the top of screen, but it doesn't lock there.
If you enter a command with long output, the prompt gets locked to the bottom while you don't scroll down.
If you enter a number of commands with short output, then you're auto-scrolled-down (like a normal terminal), while the prompt is locked to the bottom. The difference is that you can then choose to scroll-past-end, just like in an editor with scroll-past-end.