父窗口里有CS_NOCLOSE风格，子窗口如何去掉这个风格不影响父窗口

相关代码
#include "stdafx.h"
#include "resource.h"

#define MAX_LOADSTRING 100

HINSTANCE hInst;
TCHAR szTitle[MAX_LOADSTRING];
TCHAR szWindowClass[MAX_LOADSTRING];


ATOM MyRegisterClass( HINSTANCE hInstance );
ATOM Modify( HINSTANCE hInstance );
BOOL InitInstance( HINSTANCE, int );
LRESULT CALLBACK WndProc( HWND, UINT, WPARAM, LPARAM );
BOOL dump(void);

int APIENTRY WinMain(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     LPSTR     lpCmdLine,
                     int       nCmdShow )
{

MSG msg;
HACCEL hAccelTable;


LoadString(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
LoadString(hInstance, IDC_DUMP, szWindowClass, MAX_LOADSTRING);
MyRegisterClass( hInstance );

if( !InitInstance( hInstance, nCmdShow ) ) 
{
return FALSE;
}

hAccelTable = LoadAccelerators(hInstance, (LPCTSTR)IDC_DUMP);

while( GetMessage(&msg, NULL, 0, 0) ) 
{
if( !TranslateAccelerator (msg.hwnd, hAccelTable, &msg) ) 
{
TranslateMessage( &msg );
DispatchMessage( &msg );
}
}

return msg.wParam;
}

ATOM MyRegisterClass( HINSTANCE hInstance )
{
WNDCLASSEX wcex;

wcex.cbSize = sizeof(WNDCLASSEX); 

wcex.style = CS_HREDRAW | CS_VREDRAW ;
wcex.lpfnWndProc = (WNDPROC)WndProc;
wcex.cbClsExtra = 0;
wcex.cbWndExtra = 0;
wcex.hInstance = hInstance;
wcex.hIcon = LoadIcon(hInstance, (LPCTSTR)IDI_DUMP);
wcex.hCursor = LoadCursor(NULL, IDC_ARROW);
wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
wcex.lpszMenuName = (LPCSTR)IDC_DUMP;
wcex.lpszClassName = szWindowClass;
wcex.hIconSm = LoadIcon(wcex.hInstance, (LPCTSTR)IDI_SMALL);
wcex.style = wcex.style | CS_NOCLOSE;
// wcex.style = wcex.style & ~CS_NOCLOSE;
return RegisterClassEx( &wcex );
}
ATOM Modify( HINSTANCE hInstance )
{
WNDCLASSEX wcex;

wcex.cbSize = sizeof(WNDCLASSEX); 

wcex.style = CS_HREDRAW | CS_VREDRAW ;
wcex.lpfnWndProc = (WNDPROC)dump;
wcex.cbClsExtra = 0;
wcex.cbWndExtra = 0;
wcex.hInstance = hInstance;
wcex.hIcon = LoadIcon(hInstance, (LPCTSTR)IDI_DUMP);
wcex.hCursor = LoadCursor(NULL, IDC_ARROW);
wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
wcex.lpszMenuName = (LPCSTR)IDC_DUMP;
wcex.lpszClassName = szWindowClass;
wcex.hIconSm = LoadIcon(wcex.hInstance, (LPCTSTR)IDI_SMALL);
return RegisterClassEx( &wcex );
}

BOOL InitInstance( HINSTANCE hInstance, int nCmdShow )
{
   HWND hWnd;

   hInst = hInstance; 

   hWnd = CreateWindow(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
      CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInstance, NULL);

   if( !hWnd ) 
   {
      return FALSE;
   }

   ShowWindow( hWnd, nCmdShow );
   UpdateWindow( hWnd );

   return TRUE;
}


LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
int wmId, wmEvent;
PAINTSTRUCT ps;
HDC hdc;
TCHAR szHello[MAX_LOADSTRING];
LoadString(hInst, IDS_GOOD, szHello, MAX_LOADSTRING);

switch( message ) 
{
case WM_COMMAND:
wmId    = LOWORD(wParam); 
wmEvent = HIWORD(wParam); 
switch( wmId ) 
{
case IDM_EXIT:
   DestroyWindow( hWnd );
   break;
default:
   return DefWindowProc( hWnd, message, wParam, lParam );
}
break;
case WM_KEYDOWN:
return dump();
break;
case WM_PAINT:
hdc = BeginPaint (hWnd, &ps);
RECT rt;
GetClientRect( hWnd, &rt );
DrawText( hdc, szHello, strlen(szHello), &rt, DT_CENTER );
TextOut(hdc,40,40,"40",1);
EndPaint( hWnd, &ps );
break;
case WM_DESTROY:
PostQuitMessage( 0 );
break;
default:
return DefWindowProc( hWnd, message, wParam, lParam );
   }
   return 0;
}

BOOL dump( )
{
HINSTANCE hInstance =GetModuleHandleA(NULL);
HWND hWnd;
Modify(hInstance);
    hInst = hInstance; 
   hWnd = CreateWindow(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW&~WS_MINIMIZEBOX|WS_SYSMENU,
      CW_USEDE