title: Customized message box not getting in wpf
body: <p>I have a customized message box in my WPF application.
  Problem is : This message box is not showing 
  when I called it in a class that is not derived from Window.
  There is no compilation error. References are added properly.</p>
  
  <p>I coundn't call any UI components in this class.</p>
  
  <p>There occurs an exception when debugging: "The calling thread must be STA because many UI components require this"</p>