Hi Frank,
Can you please be more specific? By “UI”, do you mean widgets? There were several changes made to Widgets 2.0 in the new build, but if you want, you can continue using Widgets 1.0, as that was open-sourced as a convenience to developers who had implemented those throughout their app(s).
http://forums.coronalabs.com/topic/33421-faq-updated-to-build-1034-or-greater-including-latest-public-release-widgets-no-longer-working-read-this-first/
Otherwise, there have been no inherent changes in sprite sheet implementation, unless you’re referring to the long-ago deprecated “sprite” library, which was phased out well over a year ago. Since that point, sprites are now handled as part of the “display” library and use image sheets as their foundation.
Best regards,
Brent