I just had the same problem. The only way I got it working is this:
- I installed the full version of GWT designer as recommended by Eric Clayberg's answer (http://code.google.com/webtoolkit/tools/download-gwtdesigner.html)
- However, the instructions at http://code.google.com/webtoolkit/tools/gwtdesigner/features/gwt/gxt.html didn't work, because there simply isn't any "Google Web Toolkit > Configure for using Ext GWT (GXT)" for me either.
So instead, I created a new Project, using: New Project > WindowBuilder/GWT Designer/Model/GWT Java Project:
- I went through the Wizard, clicked Finish, and then it asked me about a GXT installation. The important thing is: You must select this now, I don't see any way to add this later. So navigate to a GXT installation folder. In that folder, I had to rename my "gxt-*.jar" to "gxt.jar" first, otherwise it couldn't be found (!).
- Now, when opening a Java file using "Open With > GWT Designer", and selecting the Design view tab at the bottom of the editor - voila, the GXT menus appear.