#### 自定义页脚
更复杂的例子,自定义了页脚的按钮,点击提交后进入 loading 状态,完成后关闭。
不需要默认确定取消按钮时,你可以把 `footer` 设为 `null`。
#### Customized Footer
A more complex example which define a customized footer button bar,
the dialog will change to loading state after clicking submit button, when the loading is over,
the modal dialog will be closed.
You could set `footer` to `null` if you don't need default footer buttons.
```html
Open
Return
Submit
Some contents...
Some contents...
Some contents...
Some contents...
Some contents...
```