This is the error I get when I try to create a new grid. I'm running GWT 2.4 with STS and the stock Jetty server.

[ERROR] [applicationScaffold] - Errors in 'jar:file:/Developer/Library/Frameworks/gxt-3.0.0-dp5/gxt-3.0.0-SNAPSHOT.jar!/com/sencha/gxt/core/client/util/'
[ERROR] [applicationScaffold] - Line 30: The constructor ImageResourcePrototype(null, SafeUri, int, int, int, int, boolean, boolean) is undefined

If you check the offending file it is passing a hardcoded null instead of a String. Here is the function call:
ImageResourcePrototype(null, url, 0, 0, width, height, false, false);
And here is the method signature:
public ImageResourcePrototype(String name, SafeUri url, int left, int top, int width, int height, boolean animated, boolean lossy)

It looks like this may be a problem with deferred binding or a compiler.

Here's another error I get:
[ERROR] [applicationScaffold] - Errors in 'jar:file:/Developer/Library/Frameworks/gxt-3.0.0-dp5/gxt-3.0.0-SNAPSHOT.jar!/com/sencha/gxt/theme/base/client/grid/'
[ERROR] [applicationScaffold] - Line 34: The attribute preventInlining is undefined for the annotation type ImageResource.ImageOptions

It looks like the annotation is defined, so why this compiler error?