单例非模态窗口的简单初始化

private static Window? _window;

[CommandMethod(nameof(OpenWpf))]
public static void OpenWpf()
{
    if(_window is not null)
        return;
    _window = new Window();
    _window.Closed += (_, _) => { _window = null; }
    Acap.ShowModelessWindow(_window);
}