This will automatically register resources found within resource_path.
If resource_path starts with "resource://", embedded Resources will be used to locate the theme
files. Otherwise, resource_path is expected to be a path on disk that may or may not exist.
If the resource_path contains a directory named "themes", that directory will be traversed for files matching the theme name
and variant. For example, if using the Adwaita theme, "themes/Adwaita.css" will be loaded. If the dark variant is being used,
"themes/Adwaita-dark.css" will be loaeded. If no matching theme file is located, "themes/shared.css" will be loaded.
When the current theme changes, the CSS will be reloaded to adapt.
The "icons" sub-directory will be used to locate icon themes.
| this | |
| resource_path |
A path to a Resources directory |