AFTER-event args for WhiteboardState.SelectionChanged$ — the selection changed (single OR multi). Selection is UI state: it is not journaled, not undoable and not persisted, so this event is a notification only (not cancelable). Fires for explicit WhiteboardState.Select / WhiteboardState.ToggleSelect / WhiteboardState.SelectMany calls AND for implicit clears (a selected item was removed, the page switched, or a restore dropped it).
The previously primary item's ID, or null when nothing was selected.
The PRIMARY selected item's ID (last added to the selection), or null when cleared.
The full multi-selection (selection order, last = primary). Empty when cleared.
AFTER-event args for WhiteboardState.SelectionChanged$ — the selection changed (single OR multi). Selection is UI state: it is not journaled, not undoable and not persisted, so this event is a notification only (not cancelable). Fires for explicit WhiteboardState.Select / WhiteboardState.ToggleSelect / WhiteboardState.SelectMany calls AND for implicit clears (a selected item was removed, the page switched, or a restore dropped it).