Earlier this week, Google shipped Eclipse Indigo. One of the features that is much of interest is the embedded Window Builder support.
"Window Builder is the framework on which SWT, Swing, and (near and dear to our hearts) GWT Designer is built on top of."
To coincide with this announcement, the team announce that 2.3.2 version of GPE is now Indigo-compatible.
For installing this update, check the following GPE quick start guide:
[Source: Google Web Toolkit Blog]