GameFrameworkViewSource supports the Activated event from the CoreApplicationView class, but that's an old class, which the most recent template doesn't use anymore (https://github.com/mono/MonoGame/wiki/Windows-8-Project-Types). The reason that this event is important is to enable game custom protocol activation.
Merge pull request #2116 from azchohfi/xamlGameProtocolActivation

GameFrameworkViewSource supports the Activated event from the CoreApplic...