So maybe its GTK version dependent, I'm using Ubuntu LTS based which is gonna be supported to 2019 and thats GTK 3.10.8.
On selecting adwaita, maybe its not "removed" but its not in the theme manager to select, so it is effectively "removed". --- Reply to this email directly or view it on GitHub: https://github.com/geany/geany/issues/807#issuecomment-164884869
