Custom Mashlet ExtJS Problem - RadioGroup

Hi mashers,

Does any one in the Community have some experience in using ExtJS for building custom mashlets?  I need some help with a problem trying to create a RadioGroup for a custom mashlet. I've posted to one of the ExtJS forums (no answer yet), but wondered if this might have been a Presto/ExtJS issue.

I'm trying to create a RadioGroup to allow the user to choose between one or other of two databases as the target for a search. Their choice will allow me to tailor the SQL in the EMML for the lookup.

I get the following error when trying to construct the RadioGroup in the mashlet container: Error: _b51[_b5c.xtype || _b5d] is not a constructor

Here's the code snippet from the experimental mashlet:

        var clinicRadGrp = {
                bodyStyle: 'padding-left:5px;',
                xtype: 'fieldset',
                title: 'RxWorks Database',
                autoHeight: true,
                //defaultType: 'radio',
                items : [{
                    xtype: 'radiogroup',
                    fieldLabel: 'Which database',
                    items:[{boxLabel: 'Item 1', name: 'rb-auto', inputValue: 1},
                           {boxLabel: 'Item 2', name: 'rb-auto', inputValue: 2, checked: true}]
                }]
                };

 Now, I've since discovered that the RadioGroup was only added in to ExtJS 2.2.  Is this error because Presto DE is using an older version of ExtJS maybe?  If so, can I upgrade it or do I need to find another way to allow the user to pick the database?

Have I overlooked something else?

Many thanks, Innes