Well, the very first Winstep application was NextSTART, back in 1999, a time when WB was still in beta and hadn't even reached version 1.0. Sometime later Winstep also released WorkShelf, which, back then, was just the Shelf (tabbed dock) plus the desktop modules.
An independent dock application, which would be called Nexus, was planned from the beginning, but I ended up taking a very looooong time to actually start working on it.
So 'Nexus' kind of became synonymous to 'vaporware', and I think most old timers eventually lost hope it would ever get done... until I got out of bed one morning and actually started working on it. Then it grew in leaps and bounds.
Because the dock and the Shelf were so closely tied together, at first Nexus only existed as a part of WorkShelf/Winstep Xtreme. Then I split it and made a free stand-alone version, which had to be pretty good and have some unique stuff if I wanted it to have a fighting chance against the currently established docks. Nexus was the first Windows dock to feature live icon reflections, for example.
As far as I know, the only docks still in active development at this point are Nexus and ObjectDock. Both backed by commercial companies - all the other free docks are dead or in limbo, and have been for quite some time. There is a lesson in there for all those who think all software should be free.