Function gtk_sys::gtk_render_background_get_clip

pub unsafe extern "C" fn gtk_render_background_get_clip(
    context: *mut GtkStyleContext, 
    x: c_double, 
    y: c_double, 
    width: c_double, 
    height: c_double, 
    out_clip: *mut GdkRectangle
)

This is supported on crate feature v3_20 only.