[C++, WinAPI] Aero Glass

#include <windows.h>
#include <commctrl.h>
#include <dwmapi.h>
#pragma comment(lib, "comctl32.lib")
#pragma comment(lib, "dwmapi.lib")

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

INT WINAPI WinMain( HINSTANCE hInst, HINSTANCE, LPSTR lStart, INT nShow )
{
    HBRUSH hbrush = CreateSolidBrush( RGB( 0, 0, 0 ) );
    WNDCLASSEX wc;
    wc.hInstance = hInst;
    wc.lpszClassName = "Klasa okna";
    wc.lpfnWndProc = WndProc;
    wc.style = CS_DBLCLKS;
    wc.cbSize = sizeof( WNDCLASSEX );
    wc.hIcon = LoadIcon( 0, IDI_WARNING );
    wc.hIconSm = LoadIcon( 0, IDI_WARNING );
    wc.hCursor = LoadCursor( 0, IDC_ARROW );
    wc.lpszMenuName = 0;
    wc.hbrBackground = hbrush;
    wc.cbWndExtra = 0;
    wc.cbClsExtra = 0;
    if( RegisterClassEx( & wc ) == 0 ) return 0;
   
    HWND hWnd = CreateWindowEx( 0, "Klasa okna", "Tytuł okna", WS_OVERLAPPEDWINDOW, 50, 50, 500, 500, 0, 0, hInst, 0 );
    ShowWindow( hWnd, nShow );
    MSG msgs;
    while( GetMessage( & msgs, 0, 0, 0 ) )
    {
        TranslateMessage( & msgs );
        DispatchMessage( & msgs );
    }
    return msgs.wParam;
}

LRESULT CALLBACK WndProc( HWND hwnd, UINT msg, WPARAM wPar, LPARAM lPar )
{
    if( msg == WM_CLOSE )
    {
        PostQuitMessage( 0 );
    }
    if( msg == WM_PAINT )
    {
        MARGINS margins = { - 1 };
        HRESULT hr = S_OK;
        hr = DwmExtendFrameIntoClientArea( hwnd, & margins );
    }
    else
         return DefWindowProc( hwnd, msg, wPar, lPar );
   
    return 0;
}