void HandlePhotoViewDragMotion (object sender, DragMotionArgs args)
{
//Widget source = Gtk.Drag.GetSourceWidget (args.Context);
//Console.WriteLine ("Drag Motion {0}", source == null ? "null" : source.TypeName);
Gdk.Drag.Status (args.Context, args.Context.SuggestedAction, args.Time);
args.RetVal = true;
}