Eclipse Working Set in 3.1M4

Eclipse Working Set in 3.1M4 refer from http://jmesnil.net/weblog/2005/01/eclipse-working-set-in-31m4.html, thx: "A cool new feature in Eclipse 3.1M4 is that you can organize projects by working sets. I've got a lot of projects in my workspace which relates to different developments. My package explorer view is quite cluttered by dozens of fine-grained projects. To improve readibility, I created different working sets (one for each related development) and I show them (Show > Working Sets). When I focus on a particular development, I Go Into the specific working set and I only see the projects of this given working set. Not groundbreaking but definitely useful." How to create working set: Go to "Project--Building Working Set--Select Working Set--New..."