RadWindow does not show in WPF app when VS Debugger.Break

Hi!

I had a trouble as the following.

Simply make a WPF app and work fine with RadWindow.Alert('good').

But, It freeze my app(nothing I can control, it just was frozen) when I have a breakpoint before showing radwindow. Could I fix it?

  private void button_Click(object sender, RoutedEventArgs e)
  {
   Debugger.Break();
   RadWindow.Alert("freeze");
  }

Best regards