ContentSharingModality.ContentAdded event

Lync 2013

Raised when any conversation participant has added a ShareableContent object to the conversation.

Namespace:  Microsoft.Lync.Model.Conversation.Sharing
Assembly:  Microsoft.Lync.Model (in Microsoft.Lync.Model.dll)

public event EventHandler<ContentCollectionChangedEventArgs> ContentAdded

Be careful about calling the ShareableContent.Present() method on the added ShearableContent object. This event is raised when content is added by any participant, while you can only invoke the Present() method on content added by the local user.