Несколько методов, обрабатывающих одно сообщение

unit ManyForm;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls;

type
  TFormManyMess = class(TForm)
    LBox: TListBox;
    Label1: TLabel;
    Button1: TButton;
    procedure FormMouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure Button1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    procedure WndProc(var Message: TMessage); override;
    procedure DefaultHandler(var Message); override;
    procedure WmLButtonDown (var Message: TWMMouse);
      message wm_lButtonDown;
    procedure MouseDown(Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer); override;
    procedure ApplicationMessage (var Msg: TMsg;
      var Handled: Boolean);
  end;

var
  FormManyMess: TFormManyMess;

implementation

{$R *.DFM}

procedure TFormManyMess.FormMouseDown(Sender: TObject;
  Button: TMouseButton; Shift: TShiftState;
  X, Y: Integer);
begin
  if Button = mbLeft then
    LBox.Items.Add (Format ('%s in (%d, %d)',
      ['FormMouseDown', X, Y]));
end;

procedure TFormManyMess.WndProc(var Message: TMessage);
begin
  if Message.Msg = wm_LButtonDown then
    LBox.Items.Add (Format ('%s in (%d, %d)',
      ['WndProc', LoWord (Message.LParam),
      HiWord (Message.LParam)]));
  inherited;
end;

procedure TFormManyMess.DefaultHandler(var Message);
begin
  with TMessage (Message) do
    if Msg = wm_LButtonDown then
      LBox.Items.Add (Format ('%s in (%d, %d)',
        ['DefaultHandler', LoWord (LParam),
        HiWord (LParam)]));
  inherited;
end;

procedure TFormManyMess.WmLButtonDown (var Message: TWMMouse);
begin
  LBox.Items.Add (Format ('%s in (%d, %d)',
    ['WmLButtonDown', Message.XPos, Message.YPos]));
  inherited;
end;

procedure TFormManyMess.MouseDown(Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  if Button = mbLeft then
    LBox.Items.Add (Format ('%s in (%d, %d)',
      ['MouseDown', X, Y]));
  inherited;
end;

procedure TFormManyMess.ApplicationMessage (var Msg: TMsg;
  var Handled: Boolean);
begin
  if (Msg.Message = wm_LButtonDown) and
      (Msg.hWnd = Handle) then
    LBox.Items.Add (Format ('%s in (%d, %d)',
      ['ApplicationMessage', LoWord (Msg.LParam),
      HiWord (Msg.LParam)]));
  Handled := False;
end;

procedure TFormManyMess.FormCreate(Sender: TObject);
begin
  Application.OnMessage := ApplicationMessage;
end;

procedure TFormManyMess.Button1Click(Sender: TObject);
begin
  LBox.Clear;
end;



end.