Combobox中禁止鼠标中键滚动list列表

//第1种方法
procedure TForm1.FormMouseWheel(Sender: TObject; Shift: TShiftState;
  WheelDelta: Integer; MousePos: TPoint; var Handled: Boolean);
begin
 if ActiveControl = ComboBox1 then
    Handled := True;
end;
//第2种方法(了解该方法后，以后会有助于我们处理更复杂的问题)
unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    cbb1: TComboBox;
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
  private
    { Private declarations }
     FOldWndProc:  TWndMethod;
  public
    { Public declarations }
    procedure  NewWndProc(var  Message:  TMessage);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure  TForm1.NewWndProc(var  Message:  TMessage);
begin
    if  ((Message.Msg  <>  WM_MOUSEWHEEL)  )  then
        FOldWndProc(Message);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
 FOldWndProc  :=  cbb1.WindowProc;
 cbb1.WindowProc  :=  NewWndProc;

end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  cbb1.WindowProc  :=  FOldWndProc;
end;