Components for Delphi and C++ Builder.

procedure TForm1.DBGridEh1CellMouseClick(Grid: TCustomGridEh; Cell: TGridCoord;
  Button: TMouseButton; Shift: TShiftState; X, Y: Integer;
  var Processed: Boolean);
var
  Column: TColumnEh;
begin
   if (Cell.X >= 1) and (Cell.X < DBGridEh1.Columns.Count - 2) then
   begin
     Column := DBGridEh1.Columns[Cell.X - 1];
   end
   else
   begin
     Exit;
   end;

  if (Cell.Y = 0) and (Column.FieldName = 'DateTimeField1') then
  begin
    DBGridEh1.SelectedRows.SelectAll;
  end;

end;

procedure TForm1.DBGridEh1DrawTitleCell(Grid: TCustomDBGridEh; ACanvas: TCanvas;
  const ARect: TRect; Params: TDBGridDrawTitleCellParamsEh;
  var Processed: Boolean);
var
  ForeInsideRect: TRect;
  CustomRect: TRect;
begin
  if (Params.Column.FieldName = 'DateTimeField1') then
  begin
    Grid.DrawTitleCellBackground(ACanvas, ARect, Params);
    ForeInsideRect := Params.ForeInsideRect;
    CustomRect := Params.ForeInsideRect;
    ForeInsideRect.Left := ForeInsideRect.Left + 20;
    CustomRect.Right := ForeInsideRect.Left;
    Params.ForeInsideRect := ForeInsideRect;
    Grid.DrawTitleCellForeground(ACanvas, ARect, Params);

    DrawCheckBoxEh(ACanvas.Handle, CustomRect, cbChecked, True, True, False, False);

    Processed := True;
  end;
end;