I have bundled the ExtJS theme "2brave" (created by wregen, details here: http://extjs.com/forum/showthread.php?t=46589) for ExtGWT. This easy-to-use JAR file can be used the same way as "Slate" theme described here: http://extjs.com/forum/showthread.php?t=41727.
I tested this JAR with GWT 1.5.2 and Ext-GWT 1.0.4.
Insert this to your *.gwt.xml file:
Then add the JAR file to your classpath.
Then add this to your ExtGWT Java code:
And then register the theme as follows:
The attached file gxt-theme-brave-1.0.zip needs to be renamed to gxt-theme-brave-1.0.jar and then included in your ExtGWT project.