Как перехватить события в неклиентской области формы, в заголовке окна, например

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
  private
    {Private declarations}
    procedure WMNCMOUSEMOVE(var message: TMessage); message WM_NCMOUSEMOVE;
  public
    {Public declarations}
end;

var
  Form1: TForm1;

implementation
{$R *.DFM}

procedure TForm1.WMNCMOUSEMOVE(var message: TMessage);
var
  s: string;
begin
  case message.wParam of
    HTERROR: s:= 'HTERROR';
    HTTRANSPARENT: s:= 'HTTRANSPARENT';
    HTNOWHERE: s:= 'HTNOWHERE';
    HTCLIENT: s:= 'HTCLIENT';
    HTCAPTION: s:= 'HTCAPTION';
    HTSYSMENU: s:= 'HTSYSMENU';
    HTSIZE: s:= 'HTSIZE';
    HTMENU: s:= 'HTMENU';
    HTHSCROLL: s:= 'HTHSCROLL';
    HTVSCROLL: s:= 'HTVSCROLL';
    HTMINBUTTON: s:= 'HTMINBUTTON';
    HTMAXBUTTON: s:= 'HTMAXBUTTON';
    HTLEFT: s:= 'HTLEFT';
    HTRIGHT: s:= 'HTRIGHT';
    HTTOP: s := 'HTTOP';
    HTTOPLEFT: s:= 'HTTOPLEFT';
    HTTOPRIGHT: s:= 'HTTOPRIGHT';
    HTBOTTOM: s:= 'HTBOTTOM';
    HTBOTTOMLEFT: s:= 'HTBOTTOMLEFT';
    HTBOTTOMRIGHT: s:= 'HTBOTTOMRIGHT';
    HTBORDER: s:= 'HTBORDER';
    HTOBJECT: s:= 'HTOBJECT';
    HTCLOSE: s:= 'HTCLOSE';
    HTHELP: s:= 'HTHELP';
    else
      s:= '';
  end;
  Form1.Caption := s;
  message.Result := 0;
end;

end.