flutter webview (plugin) occluding popup menu

[dwn]

I'm using flutter_webview_plugin, and I need to display a popup menu on top of it. However, the menu does not appear unless I resize the webview so that it does not occlude it. There do not seem to be any elevation/z-index options. How can I place a popup menu on top of the webview?

Thank you

Dan N

In case it matters - here's how I launch the webview:

flutterWebviewPlugin.launch(nextUrl, clearCache: clearCache,
    rect: new Rect.fromLTWH(
        0.0, 0.0,
        size.width, size.height - 45),
    userAgent: kAndroidUserAgent);

Here's how I set the popup menu (opens OnTap from a GestureDetector column):

final result = await showMenu(
  position: new RelativeRect.fromLTRB(size.width * .5, size.height - 210, size.width, size.height - 45),
  context: context,
  items: <PopupMenuItem<String>>[
    const PopupMenuItem<String>(
        child: Text('ENGLISH'), value: 'ENGLISH'),
    const PopupMenuItem<String>(
        child: Text('ESPANOL'), value: 'ESPANOL'),
    const PopupMenuItem<String>(
        child: Text('About'), value: 'About'),
  ],
);