Tk_MeasureChars(3tk) on Linux
The text e0ad8df11bb0, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch) shipped it. The page shows this text now.
routines to measure and display simple single-line strings.