c++ GUI CONTROL

LRESULT CALLBACK DialogProc(HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    HWND cboShutdown_After;
    HWND cboTimer;
    cboShutdown_After = GetDlgItem(hwndDlg, IDD_Shutdown_After_CBO);
    cboTimer = GetDlgItem(hwndDlg, IDD_Timer_CBO);
    const char *Shutdown_After[3] = { "(Choose your process)","Shutdown After","Restart After" };
    const char *Timer[6]={"(Select the time to process)" ,"Now", "5 mins", "15 mins", "30 mins", "1 hour"};
    int Sel1 = SendMessage(cboShutdown_After, CB_GETCURSEL, 0, 0);
    int Sel2 = SendMessage(cboTimer, CB_GETCURSEL, 0, 0);

    switch(uMsg)
    {
        case WM_INITDIALOG:

            cboShutdown_After = GetDlgItem(hwndDlg, IDD_Shutdown_After_CBO);
            for(int Count = 0; Count < 3; Count++)
            {
                SendMessage(cboShutdown_After,
                           CB_ADDSTRING,
                           0,
                           reinterpret_cast<LPARAM>((LPCTSTR)Shutdown_After[Count]));
            }

            cboTimer = GetDlgItem(hwndDlg, IDD_Timer_CBO);
            for(int Count2 = 0; Count2 < 6; Count2++)
            {
                SendMessage(cboTimer,
                           CB_ADDSTRING,
                           0,
                           reinterpret_cast<LPARAM>((LPCTSTR)Timer[Count2]));
            }

            SendMessage(cboShutdown_After, CB_SETCURSEL, 0, 0);
            SendMessage(cboTimer, CB_SETCURSEL, 0, 0);
            break;



        case WM_CLOSE:
            EndDialog(hwndDlg, 0);
            return TRUE;

        case WM_COMMAND:
            switch(LOWORD(wParam))
            {
                case IDD_Shutdown_After_CBO: // If the combo box sent the message,
                switch (HIWORD(wParam))
                {
                    case 1:
                    switch(Sel1)
                    {
                        case 0:
                        MessageBox(NULL,"Please select an action.","Error",MB_ICONWARNING);
                        break;

                        case 1:
                        if(MessageBox(NULL,"You have choose Shutdown.\nConfirm?","Information",MB_ICONQUESTION | MB_OKCANCEL)==IDOK)
                        {
                            //Do shutdown here
                            MessageBox(NULL,"You have confirm for Shutdown.","Information",MB_ICONINFORMATION);

                        }
                        else
                        {
                            return 0;
                        }
                        break;

                        case 2:
                        if(MessageBox(NULL,"You have choose Restart.\nConfirm?","Information",MB_ICONQUESTION | MB_OKCANCEL)==IDOK)
                        {
                            //Do shutdown here
                            MessageBox(NULL,"You have confirm for Restart.","Information",MB_ICONINFORMATION);
                        }
                        else
                        {
                            return 0;
                        }
                        break;
                    }
                    break;
                }
                break;

        case IDD_Timer_CBO:
            switch (HIWORD(wParam))
            {
                case 1:
                switch(Sel2)
                {
                    case 0:
                    MessageBox(NULL,"Please select a time.","Error",MB_ICONWARNING);
                    break;

                    case 1:
                    MessageBox(NULL,"Press apply to perform the action immediately.","Information",MB_ICONINFORMATION);
                    break;

                    case 2:
                    MessageBox(NULL,"Press apply to perform the action after 5 minutes.","Information",MB_ICONINFORMATION);
                    break;

                    case 3:
                    MessageBox(NULL,"Press apply to perform the action after 15 minutes.","Information",MB_ICONINFORMATION);
                    break;

                    case 4:
                    MessageBox(NULL,"Press apply to perform the action 30 minutes.","Information",MB_ICONINFORMATION);
                    break;

                    case 5:
                    MessageBox(NULL,"Press apply to perform the action 1 hour.","Information",MB_ICONINFORMATION);
                    break;
                }
                break;
            }
            break;

        case IDC_BTN_QUIT:
            EndDialog(hwndDlg, 0);
            return TRUE;

        case IDC_BTN_APPLY:
            MessageBox(hwndDlg, "Thanks for using!", "Information", MB_ICONINFORMATION);
            return TRUE;
               }
               break;


    }
    return FALSE;
}