MiG Layout is the most versatile and flexible Java Swing and SWT Layout Manager. MiG Layout can produce flowing, grid based, absolute (with links), grouped and docking layouts and you will never have to switch to another layout manager ever again!
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.