Whenever I close the webview and reopen it, a flashing white interface appears

[JemmyWang94]

Column(
children: [
Container(height: 30, color: Colors.yellow, child: ElevatedButton(onPressed: (){
setState(() {
showBrowser = !showBrowser;
});
}, child: Container(color: Colors.blue)),),
Expanded(child: showBrowser ? Container(color: Colors.red,):ExampleBrowser()),
],
)

I use this code to add a button to control the display and hiding of webview.

7C1D4652BD4EFFCC1A412414AF04A7A5.mp4

[YangLang116]

Is there a good solution?