http://nkthinker.blog.51cto.com/472430/140109
用鼠标和用键盘改变焦点事件顺序是不一样的，
按Tab键的顺序
1 Enter
2 GotFocus
3 Leave
4 Validating
5 Validated
6 LostFocus
2 GotFocus
3 Leave
4 Validating
5 Validated
6 LostFocus
电机鼠标引起的
1 Enter
2 GotFocus
3 LostFocus
4 Leave
5 Validating
6 Validated
1 Enter
2 GotFocus
3 LostFocus
4 Leave
5 Validating
6 Validated