More interesting information about Windows XP.

            else if (err == ERROR_FILE_NOT_FOUND)
            {
                /*
                 * OEM ID didn't exist, so look for the Product ID
                 */
                ShowWindow (GetDlgItem(hDlg, IDD_OEMID), SW_HIDE);
                err = RegGetStringAndRealloc(hkey, c_szAboutProductID, &lpszValue, &cb);
                if (!err)
                {
                    SetDlgItemText(hDlg, IDD_SERIALNUM, lpszValue);
                }
            }

BOOL_PTR CALLBACK AboutDlgProc(HWND hDlg, UINT wMsg, WPARAM wParam, LPARAM lParam)
{
    BOOL_PTR bReturn = TRUE;
 
    switch (wMsg)
    {
    case WM_INITDIALOG:
        _InitAboutDlg(hDlg, (LPABOUT_PARAMS)lParam);
        break;
 
    case WM_PAINT:
        {
            PAINTSTRUCT ps;
            HDC hdc = BeginPaint(hDlg, &ps);
 
            // We draw the product banner and a blue strip.  In order to support high DPI monitors
            // and scaled fonts we must scale the image and the strip to the proportions of the dialog.
            //
            // +-----------------------------+
            // | Product Banner (413x72)     |
            // |                             |
            // +-----------------------------+
            // | Blue Strip (413x5)          |
            // +-----------------------------+
 
            HDC hdcMem = CreateCompatibleDC(hdc);
            int cxDlg;
 
            {
                RECT rc;
                GetClientRect(hDlg, &rc);
                cxDlg = rc.right;
            }
 
            if (hdcMem)
            {
                BOOL fDeep = (SHGetCurColorRes() > 8);
                HBITMAP hbmBand, hbmAbout;
                int cxDest = MulDiv(413,cxDlg,413);
                int cyDest = MulDiv(72,cxDlg,413);
                UINT uID;
                UINT uXpSpLevel = 0;
                HMODULE hResourceDll = HINST_THISDLL;
 
                if (IsOS(OS_PERSONAL))
                {
                    uID = (fDeep ? IDB_ABOUTPERSONAL256 : IDB_ABOUTPERSONAL16);
                }
#ifndef _WIN64
                else if (IsOS(OS_EMBEDDED))
                {
                    uID = (fDeep ? IDB_ABOUTEMBEDDED256 : IDB_ABOUTEMBEDDED16);
                }
                else if (IsOS(OS_TABLETPC))
                {
                    uXpSpLevel = 1;
                    uID = (fDeep ? IDB_ABOUTTABLETPC256_SHELL32_DLL : IDB_ABOUTTABLETPC16_SHELL32_DLL);
                }
                else if (IsOS(OS_MEDIACENTER))
                {
                    uXpSpLevel = 1;
                    uID = (fDeep ? IDB_ABOUTMEDIACENTER256_SHELL32_DLL : IDB_ABOUTMEDIACENTER16_SHELL32_DLL);
                }
#endif // !_WIN64
                else
                {
                    uID = (fDeep ? IDB_ABOUT256 : IDB_ABOUT16);
                }
 
                // If this bitmap was added for a Windows XP service pack,
                // and lives in a special resource DLL, attempt to load it
                // now. If this fails, revert to the Professional bitmaps.
 
                if (uXpSpLevel > 0)
                {
                    hResourceDll = LoadLibraryEx(TEXT("winbrand.dll"),
                                                 NULL,
                                                 LOAD_LIBRARY_AS_DATAFILE);
 
                    if (hResourceDll == NULL)
                    {
                        hResourceDll = HINST_THISDLL;
                        uID = (fDeep ? IDB_ABOUT256 : IDB_ABOUT16);
                    }
                }
 
                // paint the bitmap for the windows product
 
                hbmAbout = LoadImage(hResourceDll,
                                     MAKEINTRESOURCE(uID),
                                     IMAGE_BITMAP, 
                                     0, 0, 
                                     LR_LOADMAP3DCOLORS);
 
                if (hResourceDll != HINST_THISDLL)
                {
                    FreeLibrary(hResourceDll);
                }
 
                if ( hbmAbout )
                {
                    HBITMAP hbmOld = SelectObject(hdcMem, hbmAbout);
                    if (hbmOld)
                    {
                        StretchBlt(hdc, 0, 0, cxDest, cyDest, hdcMem, 0,0,413,72, SRCCOPY);
                        SelectObject(hdcMem, hbmOld);
                    }
                    DeleteObject(hbmAbout);
                }
 
                // paint the blue band below it
 
                hbmBand = LoadImage(HINST_THISDLL,  
                                    MAKEINTRESOURCE(fDeep ? IDB_ABOUTBAND256:IDB_ABOUTBAND16),
                                    IMAGE_BITMAP, 
                                    0, 0, 
                                    LR_LOADMAP3DCOLORS);
                if ( hbmBand )
                {
                    HBITMAP hbmOld = SelectObject(hdcMem, hbmBand);
                    if (hbmOld)
                    {
                        StretchBlt(hdc, 0, cyDest, cxDest, MulDiv(5,cxDlg,413), hdcMem, 0,0,413,5, SRCCOPY);
                        SelectObject(hdcMem, hbmOld);
                    }
                    DeleteObject(hbmBand);
                }
 
                DeleteDC(hdcMem);
            }
 
            EndPaint(hDlg, &ps);
            break;
        }
 
    case WM_COMMAND:
        EndDialog(hDlg, TRUE);
        break;
 
    case WM_NOTIFY:
        if ((IDD_EULA == (int)wParam) &&
            (NM_CLICK == ((LPNMHDR)lParam)->code))
        {
            SHELLEXECUTEINFO sei = { 0 };
            sei.cbSize = sizeof(SHELLEXECUTEINFO);
            sei.fMask = SEE_MASK_DOENVSUBST;
            sei.hwnd = hDlg;
            sei.nShow = SW_SHOWNORMAL;
            sei.lpFile = TEXT("%windir%\\system32\\eula.txt");
 
            ShellExecuteEx(&sei);
        }
        else
        {
            // WM_NOTIFY not handled.
            bReturn = FALSE;
        }
        break;
 
    default:
        // Not handled.
        bReturn = FALSE;
    }
    return bReturn;
}

//  --------------------------------------------------------------------------
//  CTooltip::Show
//
//  Arguments:  <none>
//
//  Returns:    <none>
//
//  Purpose:    Shows the tooltip window.
//
//  History:    2000-06-12  vtan        created
//  --------------------------------------------------------------------------
 
void    CTooltip::Show (void)                                                 const
 
{
    TOOLINFO    toolInfo;
 
    ZeroMemory(&toolInfo, sizeof(toolInfo));
    toolInfo.cbSize = sizeof(toolInfo);
    toolInfo.uId = PtrToUint(_hwnd);
    (LRESULT)SendMessage(_hwnd, TTM_TRACKACTIVATE, TRUE, reinterpret_cast<LPARAM>(&toolInfo));
}