1 if the first column is a RowNumberColumnDef, otherwise 0 – the offset of the built-in columns that are
bound to "the first column": the CheckboxColumnDef, the tree arrow and the checkbox of
showCheckboxWihoutExtraColumn sit at this index (behind the row numbers).
1 if the first column is a RowNumberColumnDef, otherwise 0 – the offset of the built-in columns that are bound to "the first column": the CheckboxColumnDef, the tree arrow and the checkbox of
showCheckboxWihoutExtraColumnsit at this index (behind the row numbers).