I haven[he]#039[/he]t used the Fast Light Toolkit (FLTK) for anything serious yet, but I[he]#039[/he]m a fan of the C++ GUI toolkit that[he]#039[/he]s pretty simple to learn and (in my experience) reliable even across updates. When I found out that there was a desktop environment built with FLTK, I was eager to try it—and I was quickly glad I did. The Equinox Desktop Environment (EDE) is a fast and simple desktop written in C++ and FLTK for Unix desktops.

Source: LXer – Chill out with the Linux Equinox Desktop Environment