void show_mmo_buttons(IMultimediaOwner mmowner) {
     _mmowner = mmowner;
     _appbar.Buttons.Clear();
     foreach (var btn in _mmobuttons) {
         _appbar.Buttons.Add(btn);
     }
     _back_key = Disposable.Create(() => _page.BackKeyPress -= backkeyhandler);
     _page.BackKeyPress += backkeyhandler;
 }
 internal static IQueryable<MultimediaObject> Multimedia(IMultimediaOwner owner, DiversityDataContext ctx)
 {
     return from mmo in ctx.MultimediaObjects
            where mmo.OwnerType == owner.EntityType && mmo.RelatedId == owner.EntityID
            select mmo;
 }