Complete Dennis the Menace" volumes that Fantagraphics Books has been putting out before, but after only six volumes the series seems to have stalled. The last volume came out back in 2009. We had no new volumes during 2010 and Dennis the Menace isn't even mentioned in the Fantagraphics spring/summer 2011 distributor release catalog . This along with disturbing rumors of the first six volumes showing up as remaindered books does not bode well for future releases. I do hope they continue releasing volumes in the "Complete Dennis the Menace" series but the future looks bleak.
CORRECTION: The last volume (Volume 6) actually came out February 2, 2010. For some reason I thought it came out in November or December of 2009. In any event, it's been almost a year and no new volumes have been announced. :-(