I noticed today because I have a mouse wheel that can unlock and spin that it is possible to scroll very far past the end of a text tab in PICO-8, and then I have to spin it all the way back up. Even if there's no white space populating the document. I would expect scrolling to stop when the last character hits the top or just above the top of the screen or something like that. Hard to illustrate with a gif since you can't know when I'm using the mouse wheel (except by a pause and the cursor is jittering cause i'm hammering the mouse wheel down a bunch of times then up), but, here's one anyway.