The brand of the rows an action shows over one of its screen's own item
lists (itemHandlesOf): List is that list's declaration. The run function
does not know the handle the action will be bound to, so the rows are typed
with the generic ScreenHandle as their host; the binding retypes them from
the handle the action is called on (Self), so they are the very type of
that handle's own list — interchangeable with it — and a row's origin is
that handle. Type only, like ScreenEdgeBound: the
property never exists on the array.
The brand of the rows an action shows over one of its screen's own item lists (
itemHandlesOf):Listis that list's declaration. The run function does not know the handle the action will be bound to, so the rows are typed with the genericScreenHandleas their host; the binding retypes them from the handle the action is called on (Self), so they are the very type of that handle's own list — interchangeable with it — and a row'soriginis that handle. Type only, likeScreenEdgeBound: the property never exists on the array.