I am using Geany in Linux Mint and Kubuntu, so I comfortable with KDE and GTK. This problem is identical in both and has nothing to do with a selected color scheme. Dark system themes are not always preferred.
![231011_0533_toolbar_icons_are_invisible_in_Kubuntu_light_themes](https://github.com/geany/geany/assets/10367016/59a0612a-d439-44be-b4ac-e99b3...)