TOPIC:

procedure TsCustomWorksheetGrid.AutoAdjustColumn(ACol: Integer);
var
  gRow: Integer;  // row in grid coordinates
  r: Cardinal;
  lastRow: Cardinal;
  w, maxw: Integer;
  txt: String;
begin
  if Worksheet = nil then
    exit;

  lastRow := Worksheet.GetLastOccupiedRowIndex;
  maxw := -1;
  for r := 0 to lastRow do
  begin
    gRow := GetGridRow(r);
    txt := GetCellText(ACol, gRow);
    PrepareCanvas(ACol, gRow, []);
    w := Canvas.TextWidth(txt);
    if (txt <> '') and (w > maxw) then maxw := w;
  end;
  if maxw > -1 then
    maxw := maxw + 2*constCellPadding
  else
    maxw := DefaultColWidth;

 if Acol<Worksheet.GetLastOccupiedColIndex then  //LINE TO FIX THE PROBLEM

  ColWidths[ACol] := maxW;
  HeaderSized(true, ACol);
end;