We need to fetch the area value for the origin, not for the clip.
GtkCssArea origin;
cairo_rectangle_t image_rect;
- origin = _gtk_css_area_value_get (_gtk_style_context_peek_property (bg->context, GTK_CSS_PROPERTY_BACKGROUND_CLIP));
+ origin = _gtk_css_area_value_get (_gtk_style_context_peek_property (bg->context, GTK_CSS_PROPERTY_BACKGROUND_ORIGIN));
/* The default size of the background image depends on the
background-origin value as this affects the top left