We'd like to define a custom Ext.data.Type and use this in our Model.
We discovered a problem with the Boolean default type -- in that it is case sensitive. We discovered this while working with an Ajax proxy to a server that returns boolean values as 'True/False'. The Ext.data.Types.BOOL type is case sensitive and treats them all as false. Of course we could define 'convert()' methods for every field sent back from the server (which is what we have done) -- but is would seem preferable to solve this with a sensible type definition.