Identify visibility index of column inside virtual array of visible-only columns. If Visible property of column is False, return value is -1. This property is zero-based.

property VisibleIndex: Integer read GetVisibleIndex;

If all columns are visible VisibleIndex is equal to Position.

Example

if NxTextColumn61.VisibleIndex = 0 then
begin
  // This column is first visible and painted column
end;