var
    workhourstart: TDateTime;
    workhourend: TDateTime;
    lunchhourstart: TDateTime;
    lunchhourend: TDateTime;

procedure TForm4.FormCreate(Sender: TObject);
begin
  Planner1.PositionGap := 10;

  workhourstart := EncodeTime(8,0,0,0);
  workhourend := EncodeTime(17,0,0,0);
  lunchhourstart := EncodeTime(12,0,0,0);
  lunchhourend := EncodeTime(13,0,0,0);
end;

procedure TForm4.Planner1PositionGapProp(Sender: TObject; Position,
  Index: Integer; ABrush: TBrush; APen: TPen);
var
  dt: TDateTime;
begin
  dt := Frac(Planner1.CellToTime(Position, Index));

  if (dt >= workhourstart) and (dt <= workhourend) then
  begin
    ABrush.Color := clYellow;
    APen.Color := clYellow;
  end;


  if (dt >= lunchhourstart) and (dt <= lunchhourend) then
  begin
    ABrush.Color := clWebOrange;
    APen.Color := clWebOrange;
  end;

end;