Hi,
Slate theme is officially not added by ExtJS team for 3.0. The person who made the Slate theme has not yet updated it. As per my last find on Ext JS forum, he is updating it. Keeping fingers crossed...
Any updates on the status of this theme? Our application is built with this theme, and management will not allow upgrade to v1.0 if Slate theme is not available. The thread at ExtJS has been pretty quite but there seems to be a semi-working version of this theme available.