Thanks lossendae, for this..
btw, going to ExtJS 4 will definitively not be trivial but most 3.x applications are going to be compatible with the help of a dedicated compatibility layer that will be provided by the Ext team for the 4.0 release.
I was worried about the extras... and the need to rewrite all of them,
but if there is going to be a compatibility layer, then it is OK.
We need to start writing more Extras, not just Shaun, and I think this
can be a stopper because are people going to learn how to make them using
Extjs 3 and then have to do it all over again using Extjs 4 (that is why
I suggested jquery, that and I have already seen everything Extjs does
done using jQuery et al (jqueryUI, jqueryTemplates, etc))