Cấu hình định dạng ngày tháng, thời gian trên Windows cho ứng dụng Winform

private void button1_Click(object sender, EventArgs e)
{
    RegistryKey rk = Registry.CurrentUser.OpenSubKey(@"Control Panel\International", true);
    rk.SetValue("sTimeFormat", "HH:mm:ss"); // HH for 24hrs, hh for 12 hrs
}

private void button2_Click(object sender, EventArgs e)
{
    RegistryKey rk = Registry.CurrentUser.OpenSubKey(@"Control Panel\International", true);
    rk.SetValue("sTimeFormat", "dd/MM/yyyy"); 
}

public const int LOCALE_USER_DEFAULT = 0x00000400;
public const int LOCALE_SSHORTDATE = 0x0000001F;
public const int LOCALE_STIMEFORMAT = 0x1003;
public const int LOCALE_SSHORTTIME = 0x0079;

public const int BSF_QUERY = 0x00000001;
public const int BSF_IGNORECURRENTTASK = 0x00000002;
public const int BSF_FLUSHDISK = 0x00000004;
public const int BSF_NOHANG = 0x00000008;
public const int BSF_POSTMESSAGE = 0x00000010;
public const int BSF_FORCEIFHUNG = 0x00000020;
public const int BSF_NOTIMEOUTIFNOTHUNG = 0x00000040;
public const int BSF_MSGSRV32ISOK = unchecked((int)0x80000000);
public const int BSF_MSGSRV32ISOK_BIT = 31;

public const int BSM_ALLCOMPONENTS = 0x00000000;
public const int BSM_VXDS = 0x00000001;
public const int BSM_NETDRIVER = 0x00000002;
public const int BSM_INSTALLABLEDRIVERS = 0x00000004;
public const int BSM_APPLICATIONS = 0x00000008;
public const int BSM_ALLDESKTOPS = 0x00000010;

public const int WM_WININICHANGE = 0x001A;

[DllImport("Kernel32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
public static extern Boolean SetLocaleInfo(int Locale, int LCType, string lpLCData);

[DllImport("User32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
public static extern int BroadcastSystemMessage(int flags, ref int lpInfo, uint Msg, uint wParam, IntPtr lParam);

if (SetLocaleInfo(LOCALE_USER_DEFAULT, LOCALE_SSHORTDATE, "dd/MM/yyyy"))
{
    int dwRecipients = BSM_APPLICATIONS | BSM_ALLDESKTOPS;
    string sString = "intl";
    GCHandle GCH = GCHandle.Alloc(sString, GCHandleType.Pinned);
    IntPtr pString = GCH.AddrOfPinnedObject();
    BroadcastSystemMessage(BSF_FORCEIFHUNG | BSF_IGNORECURRENTTASK | BSF_NOHANG | BSF_NOTIMEOUTIFNOTHUNG, ref dwRecipients, WM_WININICHANGE, 0, pString);
}

if (SetLocaleInfo(LOCALE_USER_DEFAULT, LOCALE_SSHORTTIME, "HH:mm:ss"))
{
    int dwRecipients = BSM_APPLICATIONS | BSM_ALLDESKTOPS;
    string sString = "intl";
    GCHandle GCH = GCHandle.Alloc(sString, GCHandleType.Pinned);
    IntPtr pString = GCH.AddrOfPinnedObject();
    BroadcastSystemMessage(BSF_FORCEIFHUNG | BSF_IGNORECURRENTTASK | BSF_NOHANG | BSF_NOTIMEOUTIFNOTHUNG, ref dwRecipients, WM_WININICHANGE, 0, pString);
}

static class Program
{
    /// <summary>
    /// The main entry point for the application.
    /// </summary>
    [STAThread]
    static void Main()
    {
        Application.EnableVisualStyles();
        initCulturalFormattingChanges();
        Application.SetCompatibleTextRenderingDefault(false);
        Application.Run(new Form1());
    }

    private static void initCulturalFormattingChanges()
    {
        CultureInfo cultureDefinition = (CultureInfo)Thread.CurrentThread.CurrentCulture.Clone();
        cultureDefinition.DateTimeFormat.ShortDatePattern = "dd/MM/yyyy";
        cultureDefinition.DateTimeFormat.ShortTimePattern = "HH:mm:ss";
        Thread.CurrentThread.CurrentCulture = cultureDefinition;
    }
}