title: Windows 8 Gridview press and hold to select + appbar commands
body: <p>I'm developing a Windows 8.1 application in XAML/C# for touch devices and run into the following: I have a GridView where a list of items is shown which are styled as tiles. When I tap on one of these tiles, I open a different page where a detailed view of that item is shown using the following properties on the GridView:</p>
  
  <pre><code>IsItemClickEnabled="True"
  ItemClick="itemGridView_ItemClick"
  </code></pre>
  
  <p>Now I want to mimic the behaviour Windows uses on the Start screen that when you're holding a specific tile it gets selected and the AppBar shows up and offers some commands for that specific item. The commands are always the same for each item, but obviously the items aren't. When no item is selected, the AppBar shows different commands not related to a single item. On first load of the screen nothing should be selected.</p>
  
  <p>How can I achieve this behaviour?</p>