AVTKA - OpenAV
AVTKA is a plain C library for building simple user interfaces. It is developed to be easy to use, and fast to develop with.
Avtka is developed in sync with the Ctlra library, in order to provide user-interfaces for virtualized physical interfaces. As such, it is not "yet another generic user-interface library". It is a purpose built toolkit to achieve a very specific purpose - and it happens to be quite good at that. Should you use Avtka in a project of your own? Please get in contact before doing so - to make sure any expectations are aligned with reality!