Hi,
The message window has a problem with dark mode. The text color remains dark blue and dark red, which is hardly readable on a dark background:  Geany version : geany 1.35 (built on 2019-07-01 with GTK 3.24.8, GLib 2.60.2) I am running Manjaro KDE, and have tested with breeze-dark, adwaita-dark and Materia themes. The result is the same in all cases.