8.

fenster: The most minimal cross-platform GUI library

github.com/zserge/fenster

This library provides the most minimal and highly opinionated way to display a cross-platform 2D canvas. If you remember Borland BGI or drawing things in QBASIC or INT 10h- you know what I mean. As a nice bonus you also get cross-platform keyboard/mouse input and audio playback in only a few lines of code.