unit haupt;

interface

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

type
  TForm1 = class(TForm)
  private
    { Private-Deklarationen }
    procedure MouseEnter(var Msg: TMessage); message CM_MOUSEENTER;
    procedure MouseLeave(var Msg: TMessage); message CM_MOUSELEAVE;
  public
    { Public-Deklarationen }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.MouseEnter(var Msg: TMessage);
begin
  Color := clGreen;
end;

procedure TForm1.MouseLeave(var Msg: TMessage);
begin
  Color := clRed;
end;

end.