When I try to open a basic eclipse application using windowbuilder, I get an error on the design view-"This is not a GUI class and cant be edited graphically". Can anybody help me with this? I have attached the snapshot of the error.
Your mention of needing the SwingDesigner helped me. I was stumped why WindowBuilder gave me an error 'WindowBuilder Unknown GUI toolkit'. It had been weeks since I had moved from Juno to Kepler and I had been working on non-gui code so I didn't realize WindowBuilder was broken. After reading your post i installed Swing Designer and fixed the issue. Thanks!
(part of the reason I am writing this is so that Google will associate the particular error message with this solution)