`wListMenuID` keeps PRICEDITEMLISTMENU for a whole mart visit: the clerk's text
is printed from inside the mart's own routine and never goes through the display
that clears it. So every frame of the Pewter mart read "the priced buy list",
including the "Here you are! Thank you!" box the stream was looking at, whose
leftover cursor bytes belong to a two-option box.
Which screen is up is now read from the figure the game draws, the same
construction the dialogue box's `waiting` test and the YES/NO prompt already
make: a full-width box waiting for a press is the clerk (`ShopScreen::Talking`),
the item window drawn is the buy list, and the item window blank is the counter
menu.
4a1df7c3be