GestureDetector的behavior有三个类型
enum HitTestBehavior {
/// Targets that defer to their children receive events within their bounds
/// only if one of their children is hit by the hit test.
deferToChild,
/// Opaque targets can be hit by hit tests, causing them to both receive
/// events within their bounds and prevent targets visually behind them from
/// also receiving events.
opaque,
/// Translucent targets both receive events within their bounds and permit
/// targets visually behind them to also receive events.
translucent,
}
默认是deferToChild，只有当children可以接收点击事件才能响应点击。
原因：
业务场景是点击textfield跳转到新页面，所以套一层GestureDetector来响应，然后将TextField的enabled设置为false，所以默认情况下响应不了点击。解决方法：
将GestureDetector的behavior属性修改为behavior: HitTestBehavior.opaque即可。
