Adding a drop arrow to a toolbar button

// ToolBarEx.h : header file
//
#if !defined(__TOOLBAREX_H__)
#define __TOOLBAREX_H__
 
#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000

#include <afxtempl.h>
 
/////////////////////////////////////////////////////////////////////////////
// CToolBarEx window

class CToolBarEx : public CToolBar
{
public:
    CToolBarEx();
    virtual ~CToolBarEx();
 
public:
    //{{AFX_VIRTUAL(CToolBarEx)
    //}}AFX_VIRTUAL
    void SetDropArrow(UINT nCmdID, UINT nMenuID);
 
protected:
    virtual void ShowPopupMenu(UINT nCmdID);
    
    //{{AFX_MSG(CToolBarEx)
    afx_msg void OnTBDropDown(NMTOOLBAR* pNMTB, LRESULT *pResult);
    //}}AFX_MSG

    DECLARE_MESSAGE_MAP()
 
    CMap<UINT, UINT, UINT, UINT> m_mapCmd2Mnu;
};
 
/////////////////////////////////////////////////////////////////////////////

//{{AFX_INSERT_LOCATION}}
// Microsoft Visual C++ will insert additional declarations immediately before the previous line.

#endif // !defined(__TOOLBAREX_H__)

// ToolBarEx.cpp : implementation file
//

#include "stdafx.h"
#include "Resource.h"
#include "ToolBarEx.h"
 
#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif
 
/////////////////////////////////////////////////////////////////////////////
// CToolBarEx

CToolBarEx::CToolBarEx()
{
}
 
CToolBarEx::~CToolBarEx()
{
}
 
BEGIN_MESSAGE_MAP(CToolBarEx, CToolBar)
    //{{AFX_MSG_MAP(CToolBarEx)
    ON_NOTIFY_REFLECT(TBN_DROPDOWN, OnTBDropDown)
    //}}AFX_MSG_MAP
END_MESSAGE_MAP()
 
/////////////////////////////////////////////////////////////////////////////
// CToolBarEx message handlers

void CToolBarEx::ShowPopupMenu(UINT nCmdID)
{
    UINT nMenuID;
    if (!m_mapCmd2Mnu.Lookup( nCmdID, nMenuID ))
        return;
 
    CMenu menu;
    if ( menu.LoadMenu( nMenuID ))
    {
        CMenu* pPopup = menu.GetSubMenu( 0 );
        ASSERT( pPopup );
 
        CRect rc;
        SendMessage( TB_GETRECT, nCmdID, ( LPARAM )&rc );
        ClientToScreen( &rc );
 
        pPopup->TrackPopupMenu( TPM_LEFTALIGN | TPM_LEFTBUTTON | TPM_VERTICAL,
            rc.left, rc.bottom, this, &rc );
    }
}
 
void CToolBarEx::OnTBDropDown(NMTOOLBAR* pNMTB, LRESULT *pResult)
{
    ShowPopupMenu( pNMTB->iItem );
    *pResult = 0;
}
 
void CToolBarEx::SetDropArrow(UINT nCmdID, UINT nMenuID) 
{
    int iItem = CommandToIndex( nCmdID );
    if (iItem != -1)
    {
        GetToolBarCtrl( ).SendMessage( TB_SETEXTENDEDSTYLE, 0,
            ( LPARAM )TBSTYLE_EX_DRAWDDARROWS );
        
        SetButtonStyle( iItem, 
            GetButtonStyle( iItem ) | TBSTYLE_DROPDOWN );
 
        m_mapCmd2Mnu.SetAt(nCmdID, nMenuID);
    }
}

m_wndToolBar.SetDropArrow( ID_FILE_NEW,  IDR_MENU1 );
m_wndToolBar.SetDropArrow( ID_FILE_OPEN, IDR_MENU2 );