gtk/gtk.go
func (v *CssProvider) ToString() (string, error) {
	c := C.gtk_css_provider_to_string(v.native())
	if c == nil {
		return "", nilPtrErr
	}
	return C.GoString(c), nil
}
func (v *CssProvider) ToString() (string, error) {
	c := C.gtk_css_provider_to_string(v.native())
	if c == nil {
		return "", nilPtrErr
	}
	return C.GoString(c), nil
}
// ToString is a wrapper around gtk_css_provider_to_string().