Не могу присвоить OnClick для динамического объекта

unit Unit1;
 
interface
 
uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.ExtCtrls;
 
type
  TForm1 = class(TForm)
    PaintBox1: TPaintBox;
    procedure PaintBox1Paint(Sender: TObject);
    procedure PaintBox1MouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
  private
    { Private-Deklarationen }
  public
    { Public-Deklarationen }
  end;
 
var
  Form1: TForm1;
 
const
  DX = 16;
  DY = 16;
 
  ROWS = 2;
  COLS = 7;
 
implementation
 
{$R *.dfm}
 
procedure TForm1.PaintBox1MouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
var ID: Integer;
begin
  ID := X div DX + (Y div DY) * COLS;
 
  ShowMessage(
    'ID = ' + IntToStr(ID) + #13#10 +
    'X  = ' + IntToStr(X div DX) + #13#10 +
    'Y  = ' + IntToStr(Y div DY) + #13#10);
end;
 
procedure TForm1.PaintBox1Paint(Sender: TObject);
var i: Integer;
    MX, MY: Integer;
begin
 
  MX := COLS * DX;
  MY := ROWS * DY;
 
  for i := 0 to COLS do
    begin
      PaintBox1.Canvas.MoveTo(i * DX, 0);
      PaintBox1.Canvas.LineTo(i * DX, MY);
    end;
 
  for i := 0 to ROWS do
    begin
      PaintBox1.Canvas.MoveTo(0, i * DY);
      PaintBox1.Canvas.LineTo(MX, i * DY);
    end;
 
end;
 
end.

unit Unit1;
 
interface
 
uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.ExtCtrls;
 
type
  TForm1 = class(TForm)
    PaintBox1: TPaintBox;
    procedure PaintBox1Paint(Sender: TObject);
    procedure PaintBox1MouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
  private
    FX, FY: Integer;
  public
    { Public-Deklarationen }
  end;
 
var
  Form1: TForm1;
 
const
  DX = 16;
  DY = 16;
 
  ROWS = 2;
  COLS = 7;
 
implementation
 
{$R *.dfm}
 
procedure TForm1.PaintBox1MouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
var ID: Integer;
begin
 
  FX := X;
  FY := Y;
 
  PaintBox1.Repaint;
 
  ID := X div DX + (Y div DY) * COLS;
 
  ShowMessage(
    'ID = ' + IntToStr(ID) + #13#10 +
    'X  = ' + IntToStr(X div DX) + #13#10 +
    'Y  = ' + IntToStr(Y div DY) + #13#10);
end;
 
procedure TForm1.PaintBox1Paint(Sender: TObject);
var i: Integer;
    MX, MY: Integer;
begin
 
  MX := COLS * DX;
  MY := ROWS * DY;
 
  PaintBox1.Canvas.Pen.Color := clBlack;
  PaintBox1.Canvas.Brush.Color := clBlack;
 
  for i := 0 to COLS do
    begin
      PaintBox1.Canvas.MoveTo(i * DX, 0);
      PaintBox1.Canvas.LineTo(i * DX, MY);
    end;
 
  for i := 0 to ROWS do
    begin
      PaintBox1.Canvas.MoveTo(0, i * DY);
      PaintBox1.Canvas.LineTo(MX, i * DY);
    end;
 
  PaintBox1.Canvas.Pen.Color := clRed;
  PaintBox1.Canvas.Brush.Color := clRed;
 
  PaintBox1.Canvas.FloodFill(FX, FY, clBlack, fsBorder);
end;
 
end.