[sakuragi]

este es el ejemplo que dice "madriles"

Código Delphi [-]
 unit Image2;

 interface

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

 type
   TEntrarEvent=procedure(Sender:TObject) of object;
   TSalirEvent =procedure(Sender:TObject) of object;
   TImage2 = class(TImage)
   private
     { Private declarations }
     FOnEnter:TEntrarEvent;
     FOnExit :TSalirEvent;
     procedure CMMouseEnter(var msg:TMessage); message CM_MOUSEENTER;
     procedure CMMouseLeave(var msg: TMessage); message CM_MOUSELEAVE;
   protected
     { Protected declarations }
   public
     { Public declarations }
   published
     { Published declarations }
     property OnMouseEnter: TEntrarEvent read FOnEnter write FOnEnter;
     property OnMouseLeave: TSalirEvent read FOnExit write FOnExit;

   end;

 procedure Register;

 implementation

 procedure TImage2.CMMouseEnter(var msg:TMessage);
 begin
     inherited;
     {Cuando el raton entra...}
     If Assigned(FOnEnter) then FOnEnter(Self);
 end;

 procedure TImage2.CMMouseLeave(var msg: TMessage);
 begin
     inherited;
     {Cuando el raton sale}
     If Assigned(FOnExit) then FOnExit(self);
 end;

 procedure Register;
 begin
   RegisterComponents('TMania', [TImage2]);
 end;

 end.

saludos