How do I know if a WPF window is opened

Question

In a WPF window, how do I know if it is opened?

My goal to open only 1 instance of the window at the time.

So, my pseudo code in the parent window is:

<

Answer 1

public bool IsWindowOpen(string name = "") where T : Window
{
    return Application.Current.Windows.OfType().Any(w => w.GetType().Name.Equals(name));               
}