QT webview will not go fullscreen

[Bruce Steers <bsteers4@xxxxxxxxx>]

WebView1.Settings.UserAgent = "Mozilla"
WebView1.Url = "https://www.ardmediathek.de/live";

does not go fullscreen with the following error message

js: 'HTMLVideoElement.webkitSupportsFullscreen' is deprecated. Please
use 'Document.fullscreenEnabled' instead.

It seems okay with GTK3
actually with QT loading the above URL gives quite a few warning/errors...

js: The disableRemotePlayback attribute should be used in order to disable
the default Cast integration instead of using
-internal-media-controls-overlay-cast-button selector. See
https://www.chromestatus.com/feature/5714245488476160 for more details.
js: Error: Minified React error #421; visit
https://reactjs.org/docs/error-decoder.html?invariant=421 for the full
message or use the non-minified dev environment for full errors and
additional helpful warnings.
js: Error: Minified React error #418; visit
https://reactjs.org/docs/error-decoder.html?invariant=418 for the full
message or use the non-minified dev environment for full errors and
additional helpful warnings.
js: Error: Minified React error #418; visit
https://reactjs.org/docs/error-decoder.html?invariant=418 for the full
message or use the non-minified dev environment for full errors and
additional helpful warnings.
js: Error: Minified React error #418; visit
https://reactjs.org/docs/error-decoder.html?invariant=418 for the full
message or use the non-minified dev environment for full errors and
additional helpful warnings.
js: Error: Minified React error #418; visit
https://reactjs.org/docs/error-decoder.html?invariant=418 for the full
message or use the non-minified dev environment for full errors and
additional helpful warnings.
js: Error: Minified React error #422; visit
https://reactjs.org/docs/error-decoder.html?invariant=422 for the full
message or use the non-minified dev environment for full errors and
additional helpful warnings.
js: The AudioContext was not allowed to start. It must be resumed (or
created) after a user gesture on the page. https://goo.gl/7K7WLu
js: Uncaught TypeError: Cannot read property 'media' of undefined
js: Uncaught ReferenceError: t is not defined
js: 'HTMLVideoElement.webkitSupportsFullscreen' is deprecated. Please use
'Document.fullscreenEnabled' instead.

Respects
BruceS