Закрытие дочернего окна приводит к закрытию основного окна - C++ WinAPI - Ответ 10133861

#include <Windows.h>
 
// Идентификаторы окон
#define ID_FIRSTCHILD   100
#define ID_SECONDCHILD  101
#define ID_THIRDCHILD   102
 
 
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
LRESULT CALLBACK ChildProc(HWND, UINT, WPARAM, LPARAM);
 
HINSTANCE hinst;
RECT rect;
HWND child;
 
int APIENTRY WinMain(HINSTANCE hInstance,
    HINSTANCE hPrevInstance,
    LPSTR lpCmdLine,
    int nCmdShow)
{
    HWND hwnd;
    MSG msg;
    WNDCLASS w;
    hinst = hInstance;
    memset(&w, 0, sizeof(WNDCLASS));
    w.style = CS_HREDRAW | CS_VREDRAW;
    w.lpfnWndProc = WndProc;
    w.hInstance = hInstance;
    w.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
    w.lpszClassName = L"C Windows";
    w.hCursor = LoadCursor(NULL, IDC_ARROW);
    RegisterClass(&w);
    hwnd = CreateWindow(L"C Windows", L"C Windows", WS_OVERLAPPEDWINDOW,
        10, 10, 600, 480, NULL, NULL, hInstance, NULL);
    GetClientRect(hwnd, &rect);
    ShowWindow(hwnd, nCmdShow);
    UpdateWindow(hwnd);
    while (GetMessage(&msg, NULL, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return msg.wParam;
}
 
LRESULT CALLBACK WndProc(HWND hwnd, UINT Message, WPARAM wparam, LPARAM lparam)
{
    switch (Message)
    {
    case WM_LBUTTONDOWN:
    {
        SetCapture(hwnd);
        WNDCLASS w;
        memset(&w, 0, sizeof(WNDCLASS));
        w.lpfnWndProc = ChildProc;
        w.hInstance = hinst;
        w.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
        w.lpszClassName = L"ChildWClass";
        w.hCursor = LoadCursor(NULL, IDC_CROSS);
        RegisterClass(&w);
        
        child = CreateWindowEx(0, L"ChildWClass", (LPCTSTR)NULL,
            WS_CHILD | WS_BORDER | WS_VISIBLE, 0, 0,
            rect.right / 2, rect.bottom / 2, hwnd, (HMENU)(int)(ID_FIRSTCHILD), hinst, NULL);
        ShowWindow(child, SW_NORMAL);
        UpdateWindow(child);
 
        return 0;
 
    }
    case WM_LBUTTONUP:
    {
        EndDialog(child, LOWORD(wparam));
        //ReleaseCapture();
    }
    case WM_DESTROY:
    {
        PostMessage(child, WM_CLOSE, 0, 0);
        return 0;
    }
    }
    return DefWindowProc(hwnd, Message, wparam, lparam);
}
 
 
LRESULT CALLBACK ChildProc(HWND hwnd, UINT Message, WPARAM wparam, LPARAM lparam)
{
    if (Message == WM_DESTROY) {
        PostQuitMessage(0);
    }
    return DefWindowProc(hwnd, Message, wparam, lparam);
}