In the -object.xml file, remove all window-state elements, but the normal one.
It does not change anything
The min/max icons are still displayed. .
And you can still ask for the maximized or minimized state.
no exception, the portal still works as usual (with the "classic" all three states enabled).
Is it the portal core that should prevent to use these states, if not enabled ?
Or the layout strategy and rendering that should not show the icons ?
(but then, the portal should warn if we type an url that ask a state that is disabled... even it is not by clicking in the window icon).