关于改造WebBrowser控件的一些技巧，大家可以参考MSDN或者蒋晟写的一个东西，里面有讲的很详细的，今天我就说一下这个alter对话框的修改和过滤的方法：

很简单，只要咱们继承IDocHostShowUI这个接口，实现里面的ShowMessage方法就行了。

废话不多说，代码在这里：

unit Unit2;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, OleCtrls, SHDocVw,ActiveX;

type
  IDocHostShowUI = interface(IUnknown)
    ['{c4d244b0-d43e-11cf-893b-00aa00bdce1a}']
function ShowMessage(hwnd: THandle; lpstrText: POLESTR; lpstrCaption: POLESTR;dwType: longint; lpstrHelpfile: POLESTR; dwHelpContext: longint;var plResult: LRESULT): HRESULT; stdcall;
function ShowHelp(hwnd: THandle; pszHelpfile: POLESTR; uCommand: integer;dwData: longint; ptMouse: TPoint; var pDispatchObjectHit: IDispatch): HRESULT; stdcall;
end;

  TWebBrowser = class(SHDocVw.TWebBrowser,IDocHostShowUI)
protected
function ShowMessage(hwnd: THandle; lpstrText: POLESTR; lpstrCaption: POLESTR;dwType: longint; lpstrHelpfile: POLESTR; dwHelpContext: longint;var plResult: LRESULT): HRESULT; stdcall;
function ShowHelp(hwnd: THandle; pszHelpfile: POLESTR; uCommand: integer;dwData: longint; ptMouse: TPoint; var pDispatchObjectHit: IDispatch): HRESULT; stdcall;
end;

  TForm2 = class(TForm)
    WebBrowser1: TWebBrowser;
procedure FormCreate(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
  Form2: TForm2;

implementation

{$R *.dfm}

{ TWebBrowser }

function TWebBrowser.ShowHelp(hwnd: THandle; pszHelpfile: POLESTR; uCommand,
  dwData: Integer; ptMouse: TPoint; var pDispatchObjectHit: IDispatch): HRESULT;
begin
  Result := S_FALSE;
end;

function TWebBrowser.ShowMessage(hwnd: THandle; lpstrText,
  lpstrCaption: POLESTR; dwType: Integer; lpstrHelpfile: POLESTR;
  dwHelpContext: Integer; var plResult: LRESULT): HRESULT;
begin
  plResult := MessageBoxW(hwnd,PWChar(lpstrText),'不得闲测试',65);
  Result := S_OK;
end;

procedure TForm2.FormCreate(Sender: TObject);
begin
  self.WebBrowser1.Navigate(Application.ExeName + '\..\test.htm');
end;

end.