Related to and/or duplicate of at least: #2023, #1791, #1551, #894, #617, [308](https://sourceforge.net/p/geany/bugs/308/), [1019](https://sourceforge.net/p/geany/bugs/1019/).
IMO, this is definitely a silly and unexpected thing for Geany to do. By default it should print what is shown, and then offer a way to disable or invert syntax highlighting for printing.
Anyway, if anyone wants to work on this, feel free to pickup on #894 or create a newer better pull request.