Thank you for the follow up. I reviewed a bit of documentation and QPA code and I also found the following training video useful: https://www.youtube.com/watch?v=qCWWxBf6vko.
I agree that QScreen signals can provide the trigger to update the screen. However, what I haven't found out so far is how to initiate a complete refresh of all widgets and graphical elements, so that the contents of the frame buffer match the new screen resolution.

Cheers!