I need to run A() because I'm scaling the font, and that requires recomputing heights.

Things were different at the start of this project, because I scaled the font rather than reinitialize it when zooming.

I still see strange artifacts where a box seems overly long as its bottom border rises above the bottom edge of the viewport. But as it continues to rise it snaps to the right height for the text.

One benefit: now I don't need to redundantly set font twice in a single frame.