Creating a simple empty GWT Composite works fine (Using Google plugin for Eclipse), or even manually.
The crash occurs just after I see "Initializing GWT hosted mode".
I'm not sure what you mean by normal GWT Java editing functions. I've been using GPE, and created a new project using it. I also tried "Convert to GWT Project" which I believe is a WindowBuilder function, as well as the WindowBuilder "Create New... GWT -> Module" to build a sample project. Attempting to view any of these resources in design view crashes in exactly the same way, with the same console messages.
I've tried disabling compiz, as well as checking the box in the preferences labelled "disable preview window flickering workarounds".
Sample project: http://dl.dropbox.com/u/2653158/FooProject.tar.bz2
OS: Ubuntu 10.04.1 LTS x86-64
$ uname -a
Linux culver 2.6.32-24-generic #42-Ubuntu SMP Fri Aug 20 14:21:58 UTC 2010 x86_64 GNU/Linux
Eclipse 3.5.2 as installed from Ubuntu maintained packages:
||/ Name Version Description
ii eclipse 3.5.2-2ubuntu4.2 Extensible Tool Platform and Java IDE
ii eclipse-jdt 3.5.2-2ubuntu4.2 Eclipse Java Development Tools (JDT)
ii eclipse-pde 3.5.2-2ubuntu4.2 Eclipse Plug-in Development Environment (PDE
ii eclipse-platform 3.5.2-2ubuntu4.2 Eclipse platform without plug-ins to develop
ii eclipse-platform-data 3.5.2-2ubuntu4.2 Eclipse platform without plug-ins to develop
ii eclipse-plugin-cvs 3.5.2-2ubuntu4.2 Eclipse Team Integration (CVS support)
ii eclipse-rcp 3.5.2-2ubuntu4.2 Eclipse Rich Client Platform (RCP)
GWT 2.0.4 installed within Eclipse, as well as within a directory beneath my home directory. I've tried configuring WindowBuilder to use both with no change. GPE is using the built in 2.0.4.
Please let me know anything else I could provide that may assist in tracking this down.
Attached is the sample project I've tested.
To cause the crash,
1. open the EntryPoint class (ImageViewer) using "Open With" => "WindowBuilder Editor".
2. Select the Design tab