导包：
https://pub.dev/packages/universal_html
import 'package:flutter/gestures.dart';
import 'package:flutter/widgets.dart';
import 'package:universal_html/html.dart' as html;
class HoverAware extends Listener {
static final bodyContainer =
html.window.document.getElementById('body-container');
HoverAware({Widget child})
: super(
onPointerHover: (PointerHoverEvent evt) {
bodyContainer.style.cursor = 'pointer';
},
onPointerExit: (PointerExitEvent evt) {
bodyContainer.style.cursor = 'default';
},
child: child,
);
}
