interface

uses

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

type

  TForm1 = class(TForm)

  private

    { Private declarations }

  protected

    procedure WMNCHitTest(var M: TWMNCHitTest);

         message WM_NCHitTest;

  public

    { Public declarations }

  end;

var

  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.WMNCHitTest(var M: TWMNCHitTest);

begin

  inherited;

  //继承原有的消息处理函数

  if  M.Result = htClient then

  //判断消息结果是否htClient，是则将此结果改成htCaption

 M.Result := htCaption;

end;

end.