GitHub has announced Rebel, a new framework designed to improve Apple's AppKit by addressing its limitations and enhancing usability without a complete overhaul. This shift marks a move away from Twitter’s TwUI framework, which GitHub previously collaborated on, due to recent improvements in AppKit found in macOS Lion and Mountain Lion that have reduced the necessity for TwUI. Rebel aims to solve persistent issues such as NSTextField blurriness and NSScrollView performance, while introducing features like iOS-like resizable images and improved popover customization. Although Rebel is currently in alpha, it is already being used in GitHub for Mac, and the developers invite feedback and contributions as the framework evolves.