UnMashalling WebBroser Pointer

          DWORD dwBrowserPtr = NULL;
          dwBrowserPtr =dwStream //input
         
          ::CoInitialize(NULL);
          IStream** pStream = NULL ;
          pStream = reinterpret_cast<IStream**>(dwBrowserPtr);
         
         
          if( pStream == NULL )
          {
               ::CoUninitialize();
               return -1;
          }
         
          CComPtr<IDispatch> spBrowserPointer ;
          IWebBrowserQIPtr pBrowserPtr;
         
          HRESULT hr = CoGetInterfaceAndReleaseStream(*pStream,IID_IWebBrowser2,(LPVOID*)&pBrowserPtr);
          if ( hr == S_OK )
          {
               //success
          }
          else
          {
               //Failed To get browser pointer
               ASSERT(0);
              
          }

Marshalling WebBrowser Pointer

     /* ============================================================================
     #include <mshtml.h> */

     typedef CComQIPtr<IWebBrowser2,&IID_IWebBrowser2>                              IWebBrowserQIPtr;

     IStream** pStream = NULL ;
     pStream = new IStream* ; // free this memory only at the end of parsing.If you are freeing before that parse will fail

     CComPtr<IDispatch> spBrowserPointer ;         
     spBrowserPointer = APPPTR->m_pdlg->m_webBwsrCntrl.get_Application();

     IWebBrowserQIPtr pBrowserPtr;
     pBrowserPtr = spBrowserPointer;

     HRESULT hr = ::CoMarshalInterThreadInterfaceInStream(IID_IWebBrowser2,pBrowserPtr,pStream);    

     DWORD dwStream = 0;

     if( hr == S_OK )
     {
          dwStream = reinterpret_cast<DWORD>( pStream );
     }
     else
     {
          return -1;
     }

     //(*pStream)->Release(); // Do not release this.While calling CoGetInterfaceAndReleaseStream it will be automaticaly released.

     //=============================================================================

UIThreadImplementation

Create a new class and inherit CWinThread
Add dialog member object in the Thread class

#pragma once
#include "MyDialog.h"
// CMyNewThread

class CMyNewThread : public CWinThread
{
     DECLARE_DYNCREATE(CMyNewThread)

protected:
     CMyNewThread();           // protected constructor used by dynamic creation
     virtual ~CMyNewThread();

public:
     virtual BOOL InitInstance();
     virtual int ExitInstance();

     CMyDialog *m_dlg;

protected:
     DECLARE_MESSAGE_MAP()
};

BOOL CMyNewThread::InitInstance()
{    
     m_dlg = new CMyDialog();
     m_dlg->Create (IDD_DIALOG_MY, NULL);
     m_dlg->ShowWindow( TRUE );
     m_dlg->UpdateWindow();
     return TRUE;

     //return TRUE;
}

// calling the Thread
void CMainFrame::OnNewCreatenewwindow()
{
// TODO: Add your command handler code here
CWinThread *pThread = AfxBeginThread( RUNTIME_CLASS( CMyNewThread ) );
}