Sorry - in my beta4 its there, and in the docs, and in the source and on the website.
So I guess that perhaps the beta4 download may have changed (which I know Darrell has had some issues) so try downloading again to be sure. It could be possibel that the current beta4 is still got problems.
If you need it desperately, I can post my beta4 gxt.jar and you can use that (its working fine for me).