这个点语法在Pebble手表开发教程中意味着什么？

参见英文答案 > What does dot (.) mean in a struct initializer?                                    3个
我在Pebble watch app开发教程中遇到了以下代码：

// Set handlers to manage the elements inside the Window
  window_set_window_handlers(s_main_window,(WindowHandlers) {
    .load = main_window_load,.unload = main_window_unload
  });

我无法理解.load和.unload的这个任务.这是标准C吗？我认为我以前从未见过类似的语法.

(WindowHandlers) {}

.load = main_window_load,.unload = main_window_unload