On Fedora 28, Gnome-Shell does not support minimising windows and generally windows don't have maximise buttons.  Using a wayland session and running the Qt Example - "Surface", displays a window with a minimise button and a maximise button.

Clicking the minimise button results in the data visualization being hidden (disappearing) but the window remaining unchanging.  Now clicking the maximise button, results in the data visualisation being displayed and the window again remaining unchanged.

I guess that the data visualisation has chained into onMaximise() and onMinimise() signals and is responding accordingly to the window events, even though the compositor is ignoring the same events.