Singleton standard

Question

I am creating a project in C# and WPF, and I need to control instances of WPF windows, IE if I open a window in a code part with wndJanela.Show(), I want that when calling the Show() method again from another part of the code, open the same first window. For this I used the Singleton standard. But it turns out, when I call wnsJanela.Close() and try again to call the Show(), there is an error in runtime with the following message:

An unhandled Exception of type 'System.Invalidoperationexception' occurred in Presentationframework.dll Additional information: It will not be possible to set Visibility or call Show, Showdialog or Windowinterophelper.Ensurehandle after a Window is closed.

Follow my code below:

public static wndCadastroUsuario instance; //Campo publico estático que armazena a instancia da classe
    private wndCadastroUsuario() //Construtor privado
    {
        InitializeComponent();
    }

    public static wndCadastroUsuario getInstance() //Método para obter a instancia
    {
        if (instance == null)
        {
            instance = new wndCadastroUsuario();
        }

        return instance;
    }

Answer 1

if you wish to reopen the window at some point, then do not use the Close, use the method Hide