I wanted to know how to hide the navigation-bar.
And if it is possible to specify in XAML the code to SuppressSystemOverlay, as it is with the systemtray : shell:SystemTray.IsVisible="False".
I cannot find the description not even on msdn, which seems to refer to wp 8.1 build with WinRT, and my application is with silverlight.
The answer is NO, sorry. From 8.1 it is only possible through code as described in this post. However, executing hide code in the constructor like this should give a similar effect:
public MainPage()
{
InitializeComponent();
await Windows.UI.ViewManagement.StatusBar.GetForCurrentView().HideAsync();
Windows.UI.ViewManagement.ApplicationView.GetForCurrentView().SuppressSystemOverlays = true;
}