Hello,
I am the author of DOpE and Nitpicker. If you are interested in the motivation and purpose behind each of these projects, you might find my dissertation insightful:
http://www.genode-labs.com/publications/secure-gui-2009.pdf
DOpE was originally implemented for L4env. Given that L4re is somehow the evolutionary successor of L4env, I guess the L4re authors kept DOpE for historic reasons. Maybe it was deemed to be too nice to be tossed away. But to the best of my knowledge, it is not actively worked on. It is merely being kept alive.
When Christian Helmuth and me started Genode, we consciously left DOpE out of the picture. The rationale was that, on the one hand, DOpE offers too little compared to established toolkits such as Qt4. On the other hand, DOpE is quite complex and sophisticated. Properly maintaining and substantially improving it would require a significant investment of work and energy. We figured that Genode has more important areas to invest our time in. Hence, we settled on the combination of Nitpicker and Qt4.
That said, I think that the architectural approach (i.e., server-side widgets) of DOpE is in many ways superior to today's commodity GUIs. Also, compared to Qt4, DOpE is extremely light-weight, responsive, and memory efficient. So one day, I will certainly come back to it. But that day is not in sight right now.
Best regards Norman