I recently noticed that monodevelop, can change GTK theme in runtime . How do I add it in my quickly app?
If you want, you can check out my Blog Post on Python, GTK and CSS
I tried to do a little write-up on how to do it (I used it for my quickly app as well).
You can use
Where "file_name.css" is the css file you want to load (the themes in ubuntu seem to be in /usr/share/themes/THEME_NAME/gtk-3.0/) and window is the window widget you are using. If you want to load css from a string you can use