winapi - Window width and height and the resize command winapi

Question

I was wondering why if I set my window to 1440 x 900 explicitly:

HWND hWnd = CreateWindow("bla", "bla", WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, 1440/*CW_USEDEFAULT*/, 900/*CW_USEDEFAULT*/, NULL, NULL, hInstance, NULL);

When my screen is rendered it must be calling WM_RESIZE and it is passing:

    case WM_SIZE:
        screenServer.OnScreenResize( LOWORD(lParam), HIWORD(lParam) );
    break;

which comes out as 1424 x 861?

Why is that?

Answer 1

我现在可以看到正在考虑的是我的窗口的边界：