[[cHackAll]]

Código Delphi [-]
unit Unit1;

interface

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

const
 WM_XBUTTONDOWN   = $020B;
 WM_XBUTTONUP     = $020C;
 WM_XBUTTONDBLCLK = $020D;

 MK_XBUTTON1 = $20;
 MK_XBUTTON2 = $40;

type
  TForm1 = class(TForm)
  private
   procedure WMXButtonDown(var Msg: TWMMouse); message WM_XBUTTONDOWN;
   procedure WMXButtonUp(var Msg: TWMMouse); message WM_XBUTTONUP;
   procedure WMXButtonDblClk(var Msg: TWMMouse); message WM_XBUTTONDBLCLK;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.WMXButtonDown(var Msg: TWMMouse);
begin
 if Lo(Msg.Keys) = MK_XBUTTON1 then
  MessageBox(0, 'WM_XBUTTONDOWN + MK_XBUTTON1', nil, 0)
 else if Lo(Msg.Keys) = MK_XBUTTON2 then
  MessageBox(0, 'WM_XBUTTONDOWN + MK_XBUTTON2', nil, 0);
end;

procedure TForm1.WMXButtonUp(var Msg: TWMMouse);
begin
 if Lo(Msg.Keys) = MK_XBUTTON1 then
  MessageBox(0, 'WM_XBUTTONUP + MK_XBUTTON1', nil, 0)
 else if Lo(Msg.Keys) = MK_XBUTTON2 then
  MessageBox(0, 'WM_XBUTTONUP + MK_XBUTTON2', nil, 0);
end;

procedure TForm1.WMXButtonDblClk(var Msg: TWMMouse);
begin
 if Lo(Msg.Keys) = MK_XBUTTON1 then
  MessageBox(0, 'WM_XBUTTONDBLCLK + MK_XBUTTON1', nil, 0)
 else if Lo(Msg.Keys) = MK_XBUTTON2 then
  MessageBox(0, 'WM_XBUTTONDBLCLK + MK_XBUTTON2', nil, 0);
end;

end.