Cancel the live session. Does not move focus.
The editor element: the shared EditorDiv + cell input bound to the active cell and restyled as
chrome text. The host places it in its own box. null without an editable.
Commit the live session. Does not move focus.
The bar cannot start an edit: the host said so, the cell is protected or the workbook is read-only.
The formula:editor command scope, for the host's CommandScopeProvider. null without an
editable.
Whether an edit session is live.
The live edit session, or null while idle.
The selected sheet.
The active cell's coordinates on FormulaBarSession.sheet.