Rework PaneStack so that the options that generally aren't (or can't be) changed after construction are supplied to the constructor instead of being set through setter methods. This is a more sensible way of doing things in general, but also a workaround for https://code.soundsoftware.ac.uk/issues/1930, a problem that arises when reinitialising hidden property boxes in a context in which they will never be visible at all.