Something done on the screen whose answer includes fresh item handles of the
screen's own lists (a rail an action reloaded): the run function receives the
screen's handle, so it can build them with itemHandlesOf and hand the
caller items a caller can act on, instead of the visit's snapshot. The action
is otherwise action: it runs only while the screen is on top.
The action's answer is canonical for the part of the screen it refreshed;
the handle's data keeps what the visit loaded. Both are snapshots, neither
overwrites the other.
Something done on the screen whose answer includes fresh item handles of the screen's own lists (a rail an action reloaded): the run function receives the screen's handle, so it can build them with itemHandlesOf and hand the caller items a caller can act on, instead of the visit's snapshot. The action is otherwise action: it runs only while the screen is on top.
The action's answer is canonical for the part of the screen it refreshed; the handle's data keeps what the visit loaded. Both are snapshots, neither overwrites the other.