#include <windows.h>

#define ID_EDIT 1
#define ID_BUTTON 2

LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);

int WINAPI wWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PWSTR lpCmdLine, int nCmdShow) {

    MSG  msg;    
    WNDCLASSW wc = {0};
    wc.lpszClassName = L"Edit control";
    wc.hInstance     = hInstance;
    wc.hbrBackground = GetSysColorBrush(COLOR_3DFACE);
    wc.lpfnWndProc   = WndProc;
    wc.hCursor       = LoadCursor(0, IDC_ARROW);

    RegisterClassW(&wc);
    CreateWindowW(wc.lpszClassName, L"Edit control",
                  WS_OVERLAPPEDWINDOW | WS_VISIBLE,
                  220, 220, 280, 200, 0, 0, hInstance, 0);  

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

    return (int) msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, 
    WPARAM wParam, LPARAM lParam) {

    static HWND hwndEdit;
    HWND hwndButton;

    switch(msg) {

        case WM_CREATE:

            hwndEdit = CreateWindowW(L"Edit", NULL, 
                WS_CHILD | WS_VISIBLE | WS_BORDER,
                50, 50, 150, 20, hwnd, (HMENU) ID_EDIT,
                 NULL, NULL);

            hwndButton = CreateWindowW(L"button", L"Set title",
                WS_VISIBLE | WS_CHILD, 50, 100, 80, 25,
                hwnd, (HMENU) ID_BUTTON, NULL, NULL);

            break;

        case WM_COMMAND:	

            if (HIWORD(wParam) == BN_CLICKED) {

                int len = GetWindowTextLengthW(hwndEdit) + 1;
                wchar_t text[len];

                GetWindowTextW(hwndEdit, text, len);
                SetWindowTextW(hwnd, text);
            }

            break;

        case WM_DESTROY:
            PostQuitMessage(0);
            break;
    }

    return DefWindowProcW(hwnd, msg, wParam, lParam);
}