How can I make sure only one WPF Window is open at a time?

Question

I have a WPF window that I am launching from inside of a winform app. I only want to allow once instance of that WPF window to be open at a time, and not warn that user if t

Answer 1

Instead of searching the static application objects, you could instead just track this within your window, with a single static variable. Just keep a variable in the window:

private static frmCaseWpf openWindow = null; // Assuming your class name is frmCaseWpf

When you create a window, either in the initialize routines, or OnLoaded, depending on how you want it to work..:

partial class frmCaseWpf {
    public frmCaseWpf {
         this.OnLoaded += frmCaseWpf_OnLoaded;
    }

    private void frmCaseWpf_OnLoaded(object sender, RoutedEventArgs e)
    {
         if (this.openWindow != null)
         {
              // Show message box, active this.openWindow, close this
         }
         this.openWindow = this;
    }
}

If you want this window to be reusable, make sure to set this.openWindow = null; when you close the window, as well.