Get handle of IE8 window.

If you need to automate IE8, popup windows, then read this article 

Window structure go like this:

Frame Tab,
TabWindowClass,
Shell DocObject View,
Internet Explorer_Server.

So, code would go something like this:

var  
  Wnd: HWND;
  WndChild: HWND;
  IE: iwebbrowser2;
begin
  webBrowser.Quit;
  try
    Wnd := FindWindow('IEFrame', nil);
    if Wnd = 0 then //No running instance of Internet Explorer so stop!
    begin
      showmessage('No Running instance of Internet Explorer');
      exit;
    end;
    WndChild := FindWindowEX(Wnd , 0, 'Frame Tab', nil);
    Wnd := FindWindowEX(WndChild, 0, 'TabWindowClass', nil);
    Wnd := FindWindowEX(Wnd, 0, 'Shell DocObject View', nil);
    Wnd := FindWindowEX(Wnd, 0, 'Internet Explorer_Server', nil);
    if Wnd <> 0 then
    begin
      GetIEFromHWnd(Wnd, IE); //Get Iwebbrowser2 from Handle
      Result := IE;
    end;
  except
  on e: Exception do
    ShowMessage('GetIE' + e.Message);
  end;
end

function .GetIEFromHWND(WHandle: HWND; var IE: IWebbrowser2): HRESULT;
var
 hInst: HWND;
  lRes: Cardinal;
  MSG: Integer;
  pDoc: IHTMLDocument2;
  ObjectFromLresult: TObjectFromLresult;
begin
  hInst := LoadLibrary('Oleacc.dll');
  @ObjectFromLresult := GetProcAddress(hInst, 'ObjectFromLresult');
  if @ObjectFromLresult <> nil then 
  begin
    try
      MSG := RegisterWindowMessage('WM_HTML_GETOBJECT');
      SendMessageTimeOut(WHandle, MSG, 0, 0, SMTO_ABORTIFHUNG, 1000, lRes);
      Result := ObjectFromLresult(lRes, IHTMLDocument2, 0, pDoc);
      if Result = S_OK then
  (pDoc.parentWindow as IServiceprovider).QueryService(IWebbrowserApp, IWebbrowser2, IE);
    finally
      FreeLibrary(hInst);
    end;
  end;
end;

I was using myCatch, to get windows structure.

This code which I left here is just to give you idea, I hope that soon I will upload example of automation IE6, IE7 and IE8...