From Xojo Documentation
| This item was deprecated in version 2019r2.
Please use ListBox.ActiveTextControl as a replacement.
The TextArea that the ListBox uses for its editable cell operations.
To get this TextField, you must put the cell into the Inline Editable mode via the CellType or ColumnType properties and make it editable by calling the EditCell method. You can use this property to set or get the text of the ListBox cell (using SelText), set the selection, or change other properties of the ListBox’s TextField.