[cmygeHm]

xtype: 'container',
                                layout: 'column',
                                items: [
                                    {
                                        xtype: 'combo',
                                        valueField: 'id',
                                        id: 'combo_id',
                                        width: 140,
                                        displayField: 'action_name',
                                        triggerAction: 'all',
                                        selectOnFocus:true,
                                        hiddenName: 'actions',
                                        validator: function(){
                                            return true;
                                        },
                                        store: new Ext.data.JsonStore({
                                            autoLoad: true,
                                            url: 'url',
                                            fields: ['id','action_name'],
                                            root: 'rows',
                                            listeners: {
                                                load: function(){
                                                    Ext.getCmp('combo_id').setValue(1);
                                                }   
                                            }
                                        })
                                        
                                    }