the path of a filename to load, in the GLib filename encoding
%TRUE. The return value is deprecated and %FALSE will only be returned for backwards compatibility reasons if an @error is not %NULL and a loading error occurred. To track errors while loading CSS, connect to the #GtkCssProvider::parsing-error signal.
GException on failure.
Loads the data contained in @path into @css_provider, making it clear any previously loaded information.