Have you already tried changing the font to something else?
No, l'll try
what platform and what version of Geany
l'm using lubuntu 16.10. Geany-INFO: Geany 1.30, de_DE.UTF-8 Geany-INFO: GTK 2.24.30, GLib 2.50.2
I'd like to see some information on what font this is
it's the default font: Monospace