Once upon a time, I wrote a "systray widget used to load ICC color profiles with different color temperatures, either on demand or automatically based on the sun's position" in Vala: https://github.com/stefantalpalaru/iccloader

And, since there's nothing programmers love more than building new tools, a "Vala project skeleton using Autotools": https://github.com/stefantalpalaru/vala-skeleton-autotools