The following indexes can be used in methods and callback functions:
Initial Column Index (or simply Column Index)
Equals the column's index in the columns array.
Visible Column Index
Depends on the column's current location in the TreeList and changes dynamically when columns are reordered.
This index is not equal to the index set in the column.visibleIndex option. The latter is used to reorder columns.
Equals a row's order among rendered rows. This index starts from 0 and increases by 1 per row including group rows.