Adam Barth 1a3adae101 Use @required for onPressed and onChanged (#4534)
We now use the `@required` annotation to encourage developers to
explicitly set onPressed and onChanged callbacks to null when that would
disable the widget.

Fixes #287
2016-06-12 13:25:06 -07:00
..
2016-05-17 12:45:37 -07:00
2016-05-16 08:28:58 -07:00