QtWebEngineView rendition of HTML dropdown exhibits unexpected behavior

Run the simplebrowser example (no modifications needed). Navigate to https://www.w3schools.com/tags/tryit.asp?filename=tryhtml_select

Click on the dropdown to open it.

While the dropdown is still visible, click on the browser title bar and move the browser window. The dropdown list remains in place and it is possible to move the browser window completely out from under the dropdown list. No onBlur() event seems to be triggered when selecting the title bar of the main browser window.