LONG_PTR style = GetWindowLongPtrA(
    window.handle,
    GWL_EXSTYLE
);

style |= WS_EX_TOPMOST | WS_EX_LAYERED;

SetWindowLongPtrA(
    window.handle,
    GWL_EXSTYLE,
    style
);

BOOL result = SetWindowPos(
    window.handle,
    (HWND)-1,
    0,
    0,
    0,
    0,
    SWP_NOMOVE | SWP_NOSIZE | SWP_NOZORDER | SWP_FRAMECHANGED
);
assert(result);

SetLayeredWindowAttributes(window.handle, RGB(0, 0, 0), 128, LWA_ALPHA);