/// <summary>
/// Retrieves tracked shapes from the slide metadata, finds out which shapes have been deleted by the user,
/// and returns the names of those deleted shapes.
/// </summary>
private static List<string> RetrieveTrackedDeletions(PowerPointSlide slide)
{
var retrievedNameList = Common.UnserializeCollection(slide.RetrieveDataFromNotes());
if (retrievedNameList == null) return new List<string>();
var currentNames = slide.GetNameToShapeDictionary();
return retrievedNameList.Where(name => !currentNames.ContainsKey(name)).ToList();
}
