uses
  ActiveX, Shdocvw_tlb, MSHTML_TLB;

type
  TObjectFromLResult = function(LRESULT: lResult; const IID: TIID;
    wParam: wParam; out pObject): HRESULT;
  stdcall;

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;

function GetActiveIEURL: string;
var
  Document: IHtmlDocument2;
  IE: IWebBrowser2;
  Wnd: HWND;
  WndChild: HWND;
begin
  Wnd := GetForeGroundWindow;
  WndChild := FindWindowEX(Wnd, 0, 'Shell DocObject View', nil);
  if WndChild <> 0 then
  begin
    WndChild := FindWindowEX(WndChild, 0, 'Internet Explorer_Server', nil);
    if WndChild <> 0 then
    begin
      //Get Iwebbrowser2 from Handle
      GetIEFromHWnd(WndChild, IE);
      if IE <> nil then
      begin
        Result := IE.LocationURL;
        // Document := IE.Document as IHtmlDocument2;
      end;
    end;
  end;
end;

procedure TForm1.Timer1Timer(Sender: TObject);
begin
  Caption := GetActiveIEURL;
end;

da ich scheitere diesen nach C++ zu konvertieren

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/winui/winui/windowsuserinterface/windowing/windows/windowreference/windowfunctions/enumwindows.asp

alle Fenster abklappern und prüfen, ob "Internet Explorer" in den gefundenen Fensternamen vorkommt