[NumLock]

Код:

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ExtCtrls, Grids, DBGrids;

type
  TForm1 = class(TForm)
    StringGrid1: TStringGrid;
    ColorBox1: TColorBox;
    procedure StringGrid1DrawCell(Sender: TObject; ACol, ARow: Integer;
      Rect: TRect; State: TGridDrawState);
    procedure StringGrid1SelectCell(Sender: TObject; ACol, ARow: Integer;
      var CanSelect: Boolean);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

uses Types;

{$R *.dfm}

procedure TForm1.StringGrid1DrawCell(Sender: TObject; ACol, ARow: Integer;
  Rect: TRect; State: TGridDrawState);
begin
  if gdFocused in State then
  begin
    if ACol=2 then
    begin
      ColorBox1.Parent:=Self;
      ColorBox1.Left:=Rect.Left+StringGrid1.Left+2;
      ColorBox1.Top:=Rect.Top+StringGrid1.Top+2;
      ColorBox1.Width:=Rect.Right-Rect.Left;
      ColorBox1.Visible:=True;
    end;
  end;
end;

procedure TForm1.StringGrid1SelectCell(Sender: TObject; ACol,
  ARow: Integer; var CanSelect: Boolean);
begin
  ColorBox1.Visible:=False;
end;

end.