WPF Application is not closed after shutdown

Problem:
- WPF application is not closing correctly ...
- The users close application but the application is not closing.
- My application staying in background processes after closing.
- How to exit a WPF app correctly or programmatically?
- WPF (Avalon) application not closing correctly!
- The application not shuts down correctly!

Solution: 
Add Closed Event to main window like below:

    private void DXRibbonWindow_Closed(object sender, EventArgs e)
    {
        //Environment.Exit(0);
        Application.Current.Shutdown();
    }

References:
LINK1: http://stackoverflow.com/questions/810531/wpf-application-is-not-closing-correctly
LINK2: http://stackoverflow.com/questions/3543704/wpf-application-still-runs-in-background-after-closing