GtkStyleProperties provides the storage for style information that is used by GtkStyleContext and other GtkStyleProvider implementations. Before style properties can be stored in GtkStyleProperties, they must be registered with gtk_style_properties_register_property(). Unless you are writing a GtkStyleProvider implementation, you are unlikely to use this API directly, as gtk_style_context_get() and its variants are the preferred way to access styling information from widget implementations and theming engine implementations should use the APIs provided by GtkThemingEngine instead.