code: func (v *Container) ChildSetProperty(child IWidget, name string, value interface{}) error {
  	gv, e := glib.GValue(value)
  	if e != nil {
  		return e
  	}
  	cstr := C.CString(name)
  	defer C.free(unsafe.Pointer(cstr))
  
  	C.gtk_container_child_set_property(v.native(), child.toWidget(), (*C.gchar)(cstr), (*C.GValue)(unsafe.Pointer(gv.Native())))
  	return nil
  }
docs: // ChildSetProperty is a wrapper around gtk_container_child_set_property().