It’s often useful to display the current App version (per your App Manifest) for support purposes. I came across the following snippet that looks to provide the easiest option that requires no manual updates when you release a new version of your app:
VersionTextBox.Text = XDocument.Load("WMAppManifest.xml").Root.Element("App").Attribute("Version").Value;
I usually use this in my about box similar to this (add a textbox named VersionTextBox to your xaml first):
