RCLayout is a Java LayoutManager that is flexible like GridBagLayout but intuitive like GridLayout. RCLayout achieves maximum results with minimum code by using a parameter hierarchy. This layout manager is easy to learn and makes designing GUIs easy.
libwt is a SDL based c++ toolkit that provides signal & slots and a layout manager. It utilizes, when possible, the SDL framework like SDL_Mixer, SDL_Image, SDL_ttf, SDL_gfx, SDL_net etc.