We have a big project that works with extjs 3.4. Now we want to add new functionality and migrate to ext js 4.x. At the first step of migration I want to use sandboxing, but I don't want to use Ext4 namespace. In best case I want use Ext3 namespace fo ext 3.4 and Ext for 4.x. Can you advise whether this is possible and if yes, how to do it?