selection hasn't selectedItem.. i'm lost without it :shock:

Good day,
I've a great problem.

I've add a 'select' component in the Image panel, in this way:

                if ( dialogName == 'image' )
                {
                    infoTab = dialogDefinition.getContents( 'info' );                   
                     if (!infoTab.get('previewSize')){        
                        // Add a text field to the "info" tab.
                        infoTab.add( {
                            type : 'select',      
                            label : 'Preview', 
                            onChange : function() { changeImageSize(ev,this.value) }, 
                            id : 'previewSize',
                            'default' : '1',   
                            items : ComboBoxItems                
                        });     
                    };
                }

I use only the onChange event, because it is the only (i think) event that work with 'select' (why there are not onSelected or similar?)

with that event I pass 'ev', the same argument that come with

CKEDITOR.on( 'dialogDefinition', function( ev )   { ... }

and i do it

var mySelect = ev.data.definition.getContents( 'info' ).get('previewSize')

but I can't see information about the selected value....
I see Id, items, onChange listener, label, but nothig about the selected item.... thet is the only thing that I needed....

I'm lost... maybe because I'm not mighty on ckeditor or java....

Can you help me?
thank so much...

every aids will be important....