How to display login modal window atop Shell in Prism 6?
<p>My Prism 6 WPF MVVM modular application (with Unity DI) has to display modal login window atop Shell, after it has loaded, to ask user about username and password. (This is the demand of production target on my job.) I've read post at <a href="http://compositewpf.codeplex.com/discussions/58292" rel="nofollow noreferrer">http://compositewpf.codeplex.com/discussions/58292</a> but this post is describing how to display login window before displaying of Shell but my application must display login window <strong>atop</strong> Shell (so Shell must be displayed on a background). Moreover, this post describes how to do it in Prism 2 but I use Prism 6 and I want to use Prism Window(WPF) as a view for login window. Below is my application structure:</p>

<p><a href="https://i.stack.imgur.com/p2j9K.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/p2j9K.png" alt="enter image description here"></a></p>

<p>Where 'AuthrizationView.xaml is Prism Window(WPF) that is login window that has AuthrizationViewModel view model in ViewModels folder and AuthrizationModel model in Models folder in 'Authorization' project in solution. And MainWindow.xaml is Shell that has MainWindowViewModel view model in ViewModels folder in 'FlowmeterConfiguration' project in solution. So I have the following questions here:</p>

<ol>
<li>How to display login modal window atop Shell?</li>
<li>How to close login window when user click 'Login' button in this window after he or she has typed username and password in appropriate boxes?</li>
<li>How to close login window when user click 'Cancel' button in this window if he or she doesn't want to login?</li>
<li>Can login window be activated again and again to change the user by clicking on appropriate menu item in Shell?</li>
<li>Can I add keyboard shortcut support for such menu item?</li>
</ol>

<p>Your help will be appreciated highly.</p>