Cannot set non-compressed flags

[gyk]

I can't compile the example in the NWG guide:

#[derive(NwgUi)]
struct MyUi {
    #[nwg_control(flags: WindowFlags::WINDOW | WindowFlags::VISIBLE)]
    window1: nwg::Window,
}

Error message: "Compressed flags must str, got Binary".

Rust version: 1.56.0