Get Original Theme Data

Adwaita has moved its data into a so called "gresource" file and is now shipped directly bundled with GTK. To extract the theme file itself, it is required grab it out of the resource file. This can be done by issueing the following command:

Default theme

    gresource extract /usr/lib/libgtk-3.so /org/gtk/libgtk/theme/Adwaita/gtk-contained.css

Dark theme

    gresource extract /usr/lib/libgtk-3.so /org/gtk/libgtk/theme/Adwaita/gtk-contained-dark.css

GTK+ Inspector

The GTK+ Inspector can be used to identify the elements of a GTK window and the corresponding name. Those names and classes are required to be able to adjust their appearance via the gtk stylesheet/theme. This tool is disabled by default but can be enabled via gsettings:

    gsettings set org.gtk.Settings.Debug enable-inspector-keybinding true

Once it has been enabled, it can be shown by pressing + + D or + + I to automatically select the widget under the mouse pointer.