smth

#include "stdafx.h"
#include <Windows.h>

#define STRICT
#define WIN32_LEAN_AND_MEAN

#define CLASS  "wClass"
#define OVERL  "overlaped"
#define CHLD  "child"
#define POPUP  "popup"

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);

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

    LPCTSTR szClass = TEXT(CLASS);

    WNDCLASS wc = { 0 };
    wc.lpfnWndProc = WndProc;
    wc.hInstance = hInstance;
    wc.lpszClassName = szClass;
    wc.style = CS_DBLCLKS;
    wc.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);

    if (!::RegisterClass(&wc))
        return -1;

    HWND wndOverlapped = ::CreateWindow(szClass, OVERL,
        WS_OVERLAPPEDWINDOW,
        0, 0, 500, 300, NULL, NULL, hInstance, NULL);
    if (!wndOverlapped) {
        return -1;
    }

    HWND wndChild = ::CreateWindow(szClass, CHLD,
        WS_CHILD | WS_CAPTION | WS_SYSMENU| WS_MINIMIZEBOX |
        WS_MAXIMIZEBOX | WS_THICKFRAME | WS_VISIBLE,
        0, 0, 200, 150, wndOverlapped, NULL, hInstance, NULL);
    if (!wndChild) {
        return -1;
    }

    HWND wndPopup = ::CreateWindow(szClass, POPUP,
        WS_POPUPWINDOW | WS_CAPTION | WS_SYSMENU | WS_MAXIMIZEBOX |
        WS_MINIMIZEBOX | WS_VISIBLE,
        700, 150, 400, 200, wndOverlapped, NULL, hInstance, NULL);
    if (!wndPopup) {
        return -1;
    }

    ::ShowWindow(wndOverlapped, nCmdShow);

    MSG msg;
    while (::GetMessage(&msg, NULL, 0, 0)) {
        ::DispatchMessage(&msg);
    }

    return 0;
}

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message) {

    case WM_LBUTTONDOWN:
    {
        HWND main = FindWindow(CLASS, OVERL);
        HWND popup = FindWindow(CLASS, POPUP);
        HWND child = FindWindowEx(main, NULL, CLASS, CHLD);
        if (!child) child = FindWindowEx(popup, NULL, CLASS, CHLD);
        if (!IsChild(hWnd, child) && hWnd == main)
            SetParent(child, hWnd);
        else if (!IsChild(hWnd, child) && hWnd == popup)
            SetParent(child, hWnd);
        return 0;
    }

    case WM_RBUTTONDBLCLK:
    {
        HWND popup = FindWindow(CLASS, POPUP);
        if (hWnd == popup){
            if (::GetWindowLong(hWnd, GWL_EXSTYLE) & WS_EX_TOPMOST){
                SetWindowPos(popup, HWND_NOTOPMOST, 0, 0, 0, 0, SWP_NOSIZE | SWP_NOMOVE);
            }
            else {
                SetWindowPos(popup, HWND_TOPMOST, 0, 0, 0, 0, SWP_NOSIZE | SWP_NOMOVE);}
            }
        return 0;
    }

    case WM_DESTROY:
        {
        if (hWnd== FindWindow(CLASS, OVERL))
        ::PostQuitMessage(0);
        return 0;
        }
    }

    return ::DefWindowProc(hWnd, message, wParam, lParam);
}