Resolve the currently loaded content context

[ModuleDependency(typeof (EPiServer.Shell.UI.InitializationModule))]
public class CustomModule: IConfigurableModule {
  public void Initialize(InitializationEngine context) {
    context.Locate.ContentEvents().CreatedContent += CreatedContent;
    context.Locate.ContentEvents().CreatingContent += CreatingContent;
  }

  private void CreatingContent(object sender, ContentEventArgs e) {
    var currentContentContext = ServiceLocator.Current.GetInstance<CurrentContentContext>();
    // we know which content context initiated the CREATE operation        
    var currentContentLink = currentContentContext.ContentLink;

    var newlyCreatedContentLink = e.ContentLink; // --> null as at this point the ContentReference was not assigned yet
  }

  private void CreatedContent(object sender, ContentEventArgs e) {
    var newlyCreatedContentLink = e.ContentLink; // this is the ContentReference of the newly created content item
    // but we might need the ContentReference of the content that was being viewed when the CREATE operation was run
    var currentContentContext = ServiceLocator.Current.GetInstance<CurrentContentContext>();
    // this gives us the content context the editor was in
    var currentContentLink = currentContentContext.ContentLink;
  }

  public void Uninitialize(InitializationEngine context) {
    context.Locate.ContentEvents().CreatedContent -= CreatedContent;
    context.Locate.ContentEvents().CreatingContent -= CreatingContent;
  }

  public void ConfigureContainer(ServiceConfigurationContext context) {

  }
}

public class FooPageType: PageData {
  [EditorDescriptor(EditorDescriptorType = typeof (CollectionEditorDescriptor<OfferDetailsItem>))]
  public virtual IList<OfferDetailsItem> OfferDetailsItems {
    get;
    set;
  }
}

public class OfferDetailsItem {
  [Display(Order = 1)]
  [UIHint("test")]
  public string Label {
    get;
    set;
  }
}

[PropertyDefinitionTypePlugIn]
public class OfferDetailsItemPropertyList: PropertyList<OfferDetailsItem>{}

[EditorDescriptorRegistration(TargetType = typeof (string), UIHint = "test")]
public class CustomXhtmlDescriptor: StringEditorDescriptor {
  private readonly CurrentContentContext _currentContent;

  public CustomXhtmlDescriptor(CurrentContentContext currentContent) {
    _currentContent = currentContent;
  }

  public override void ModifyMetadata(ExtendedMetadata metadata, IEnumerable<Attribute> attributes) {
    base.ModifyMetadata(metadata, attributes);

    var ownerContent = metadata.FindOwnerContent(); // --> will return null because the object we annotate is not ContentData but simple POCO
    var currentContent = _currentContent.ContentLink; // --> will return correct page id
  }
}