public async Task CloseDocumentEditor (IDocumentEditor editor, bool unbindUI, bool deleteThumbnail, bool reloadThumbnail)
		{
			var docRef = editor.DocumentReference;
			if (docRef == null)
				return;
			
			var doc = docRef.Document;
			if (doc == null)
				return;

			Debug.WriteLine ("CLOSE " + docRef.File.Path);

			if (!doc.IsOpen)
				return;
			docRef.IsNew = false;

			Settings.LastDocumentPath = "";

			try {
				await docRef.Close ();

				editor.UnbindDocument ();
				if (unbindUI) {
					editor.UnbindUI ();
				}

				InvalidateThumbnail (docRef.File, deleteThumbnail:deleteThumbnail, reloadThumbnail:reloadThumbnail);

			} catch (Exception ex) {
				Debug.WriteLine (ex);
			}
		}