Generally double-clicking a window title bar when the window is not maximised, will maximise the window

Generally double clicking a window title bar when the window is maximised, will restore the window to its previous size.

Running a qt application under wayland and double clicking the title bar currenly has not effect.

Under gnome-shell, windows dont generally have maximise and minise buttons by default, hence one gets used with using this double-click short-cut and its surprising when it does not work.