the "surface" problem was that delegate's lastDisplayedDate property wasn't
updated - did so as a quick fix.
another misbehaviour is that today isn't updated. Currently, there's no way to
do so - it's a notification-only property of the monthView.
Sure there is other state unkept ... which leads to the core problem: waaaayyy
tooo much state kept as aliases in the BasicMonthViewUI. Will open a task to
cleanup. Which unfortunately will hurt LF-implementations.