Shell.xaml

<Window x:Class="HelloWorld.Shell"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:prism="http://www.codeplex.com/prism"
        Title="Hello World">
  <ItemsControl prism:RegionManager.RegionName="MainRegion">
    <ItemsControl.ItemsPanel>
      <ItemsPanelTemplate>
        <Grid />
      </ItemsPanelTemplate>
    </ItemsControl.ItemsPanel>
  </ItemsControl>
</Window>