OptionalfillHack Ignore fill.
The selection moved on a committed leave-key. This is the ONLY thing the input needed the sheet
for, so it takes the selection directly — the grid and the editor then move the SAME selection
(pass sheet.getSelection() for a sheet-backed grid, or the grid's own DefaultSelection).
Options bound once (by the app) when building the input — the SDK context the cell can't supply.