Using my own framework with many sorts of buttons, checkboxes, movable lists, popups, animation presets, with scene changer, asynchronous media loading/caching and etc. But I don't think anybody can use that easily now. There's not so many experience of making code public. I've started new project on the same basis. So it might involve to better framework later with comments, tutorial and straight forward usage. It's still 100% Sparrow so no additional restrictions.