A searchable checklist of values with a tri-state Select All and a count line — the filter
dropdown's Values body, and any other "which of these" choice.
Remarks
The list holds values and nothing else. What acts on them sits on the search line: Select All
before the field, over the rows in view, and Add after it, for a host that takes typed values.
A blank is not a value and has no row; whether blanks pass is the host's to ask.
Reads no cells: the host supplies the items and owns the checked set (by text). The search
narrows the VIEW only: Select All acts on the rows in view, rows narrowed away keep their state,
and what the host applies is the whole set (Sheets' rule, not Excel's replace-with-results).
The search field keeps the focus; Up/Down move the list's highlight, Space toggles the
highlighted rows, Enter applies, Escape clears the search and then closes.
With dates, the leading items are listed as a tree (Excel's year › month › day): a node's
checkbox is the state of its items, its row toggles them all, and its disclosure (or Left and
Right on the highlighted row, with nothing typed) folds it. Collapsing hides the member rows
from the view; they keep their state.
The root wears the grid's surface and mode, so the list looks like the cells it stands for even
inside chrome of another color.
A searchable checklist of values with a tri-state Select All and a count line — the filter dropdown's Values body, and any other "which of these" choice.
Remarks
The list holds values and nothing else. What acts on them sits on the search line: Select All before the field, over the rows in view, and Add after it, for a host that takes typed values. A blank is not a value and has no row; whether blanks pass is the host's to ask.
Reads no cells: the host supplies the items and owns the checked set (by text). The search narrows the VIEW only: Select All acts on the rows in view, rows narrowed away keep their state, and what the host applies is the whole set (Sheets' rule, not Excel's replace-with-results). The search field keeps the focus; Up/Down move the list's highlight, Space toggles the highlighted rows, Enter applies, Escape clears the search and then closes.
With
dates, the leading items are listed as a tree (Excel's year › month › day): a node's checkbox is the state of its items, its row toggles them all, and its disclosure (or Left and Right on the highlighted row, with nothing typed) folds it. Collapsing hides the member rows from the view; they keep their state.The root wears the grid's surface and mode, so the list looks like the cells it stands for even inside chrome of another color.