"select your GWT module file and right-click to select the Google Web Toolkit > Configure for using Ext GWT (GXT)" http://code.google.com/webtoolkit/tools/gwtdesigner/features/gwt/gxt.html
Read setup.txt in ext-gwt zip:
STEP 1 -> Create a Google Web Application Project project within Eclipse.
Copy the contents of the /resources folder in the download to a {foldername} location within your war folder.
Substitute {foldername} with the name of the folder you've created for resources within your war folder.
STEP 3 -> Add the following stylesheet to your host page.
STEP 3b -> If you are using Charts, add the following script to your host page.
STEP 4 -> Add the following entry to you projects module xml file.
STEP 5 -> Eclipse Setup (should be similar for other development environments)
These instructions assume you have a existing project and launch configuration.
Add gxt.jar to the project.
a. Right click on project name in 'Package Explorer'.
b. Select 'Properties' from content menu.
c. Select 'Java Build Path'.
d. Select 'Libraries' tab.
e. Add the gxt.jar either with 'Add JARs...' or 'Add External JARs...'.
Add GXT jar to launch configuration.
a. Choose Run / Open Run Dialog.
b. Select your appropriate launch configuration under 'Java Application'.
c. Select the 'Classpath' tab.
d. Add the gxt.jar to the classpath.