uil (short for User Interface Library) is a minimal Windows UI library in C++14. uil is a header-only implementation compatible with VC2013, Intel C++ 2013 and mingw 4.9.2
This system provides printed and cursive handwriting recognition service as a shared library on GNU/Linux/Unix systems.
Until someone writes another client, try the S/HIP:
https://sourceforge.net/projects/ship-project/
Coypu is an abstract layer, graphic widgets implementation. It is written in C and is highly portable to most architectures and software/hardware backends (X11, Directfb, GLUT, SDL, WIN32). Being fast and light, it's mainly targeted at embedded devices.