ref: b9f2b8c6a28c2d4744119c7254767a0f1b51ed2e
dir: widget/CONVENTIONS
• widgets that encapsulate other widgets: - take ownership (responsible for freeing, etc) - are responsible for ensuring their subwidgets don't stomp all over the screen • widgets should make sure global state is consistent with how it was when their functions were invoked (i.e. if you touch screen->clipr, restore it before returning, etc) • Widget->draw returns size of widget • event handling functions return 1 for when they handled the event themselves and 0 when they didn't