C / C++ / MFC

////////////////////////////////////////////////////////////////////////////////////
// THIS IS FOR SETTING THE OFF BITMAP

// Get the old ImageList and then destroy it.
HIMAGELIST hOld = (HIMAGELIST)::SendMessage(m_wndToolBar, TB_GETIMAGELIST, 0, 0);
ImageList_Destroy(hOld);

// Set up image lists.
CImageList imageList;
CBitmap    bitmap;

// Create and set the toolbar image list.
bitmap.LoadBitmap(IDB_OFF); <-- BITMAP IN RESOURCE
imageList.Create(16, 16, ILC_COLORDDB|ILC_MASK, 3, 1);
imageList.Add(&bitmap, RGB(255,0,255)); 

// Set the new image list on the toolbar
m_wndToolBar.SendMessage(TB_SETIMAGELIST, 0, (LPARAM)imageList.m_hImageList);
						
// Clean up
imageList.Detach();
bitmap.DeleteObject();
// END OF OFF BITMAP
///////////////////////////////////////////////////////////////////////////////////

///////////////////////////////////////////////////////////////////////////////////
// THIS IS FOR SETTING THE ON BITMAP

// Get the old ImageList and then destroy it.
HIMAGELIST hOld = (HIMAGELIST)::SendMessage(m_wndToolBar, TB_GETIMAGELIST, 0, 0);
ImageList_Destroy(hOld);

// Set up image lists.
CImageList imageList;
CBitmap    bitmap;

// Create and set the toolbar image list.
bitmap.LoadBitmap(IDB_ON); <-- BITMAP IN RESOURCES
imageList.Create(16, 16, ILC_COLORDDB|ILC_MASK, 3, 1);
imageList.Add(&bitmap, RGB(255,0,255)); 

// Set the new image list on the toolbar
m_wndToolBar.SendMessage(TB_SETIMAGELIST, 0, (LPARAM)imageList.m_hImageList);
						
// Clean up
imageList.Detach();
bitmap.DeleteObject();
// END OF ON BITMAP
///////////////////////////////////////////////////////////////////////////////////

CMyView::OnUpdateAppAbout(CCmdUI* pCmdUI)
{
    if (pCmdUI->m_pOther && pCmdUI->m_pOther->IsKindOf(RUNTIME_CLASS(CToolBar)))
    {
        CToolBar *pTB = (CToolBar *)pCmdUI->m_pOther;
        pTB->SetButtonInfo(pCmdUI->m_nIndex, pCmdUI->m_nID, TBBS_BUTTON, m_nAboutImage);
    }
}