Inability to Exit Fullscreen Mode using ESC Key in Qt WebEngine Video Player Example

Description:

When using the Qt WebEngine Widgets Video Player Example on macOS, it is not possible to exit fullscreen mode by pressing the ESC key, despite the popup message indicating that it should work.

Steps to Reproduce:

1. Launch the Qt WebEngine Widgets Video Player Example.
2. Enter fullscreen mode by clicking the fullscreen button or by double-clicking on the screen.
3. Attempt to exit fullscreen mode by pressing the ESC key.

Expected Results:

The video player should exit fullscreen mode when the ESC key is pressed, as indicated by the popup message.

Actual Results:

The video player remains in fullscreen mode, and the ESC key has no effect.