I try to use a new version of Extjs (4.2.0) that I think it doesn't have a big change for tab panel component, but I have some problem when I active on a tab. It always display a tab move to right. I don't know what wrong?? (pre. version 4.1.x is working ok, when active on tab, a tab didn't move)

Code:
Ext.create('Ext.panel.Panel', {
        id: 'employee-history',
        title: 'Emplyee Biograph',
        height: Ext.getBody().getViewSize().height,
        renderTo: Ext.getBody(),
        iconCls: 'icon-individual',
        bodyStyle: 'background-color:#003;',
        layout: 'fit',
        border: false,
        items: [
        {
            xtype: 'panel',
            layout: 'border',
            border: false,
            items: [
            {
                xtype: 'panel',
                region: 'west',
                border: false,
                bodyStyle: 'background: #003; color:#FFF; font-size:12px; padding:5px; padding-left:10px;',
                width: 320,
                loader: {
                    url: './data/history-general.php',
                    params: {'pid': pid, 'token':Math.random(10)},
                    autoLoad: true,
                    renderer: function(loader, response, active) {
                        var text = response.responseText;
                        loader.getTarget().update(text);
                        return true;
                    }
                }
            },{
                xtype: 'tabpanel',
                region: 'center',
                border: false,
                activeTab: 0,
                plain: false,
                items: [
                {
                    title: 'Education',
                    iconCls: 'icon-education',
                    layout: {
                        type:'fit',
                        align:'stretch',
                        pack:'start'
                    },
                    items: [employeeEducationView]
                },{
                    title: 'Assignment',
                    layout: {
                        type:'fit',
                        align:'stretch',
                        pack:'start'
                    },
                    iconCls: 'icon-all',
                    items: [employeeAssignmentView]
                },{
                    title: 'Training',
                    layout: {
                        type:'fit',
                        align:'stretch',
                        pack:'start'
                    },
                    iconCls: 'icon-working',
                    items: [employeeTrainingView]
                },{
                    title: 'Special Training',
                    layout: {
                        type:'fit',
                        align:'stretch',
                        pack:'start'
                    },
                    iconCls: 'icon-connect',
                    items: [employeeTrainingExtraView]
                },{
                    title: 'Go Aboard',
                    iconCls: 'icon-plane',
                    layout: {
                        type:'fit',
                        align:'stretch',
                        pack:'start'
                    },
                    items: [employeeTrainingExternalView]
                },{
                    title: 'Community',
                    iconCls: 'icon-community',
                    layout: {
                        type:'fit',
                        align:'stretch',
                        pack:'start'
                    },
                    items: [employeeExternalEventView]
                },{
                    title: 'Evaluation',
                    iconCls: 'icon-text',
                    layout: {
                        type:'fit',
                        align:'stretch',
                        pack:'start'
                    },
                    items: [employeeEvaluationView]
                },{
                    title: 'Special Project',
                    iconCls: 'icon-star',
                    layout: {
                        type:'fit',
                        align:'stretch',
                        pack:'start'
                    },
                    items: [employeeSpecialView]
                },{
                    title: 'Salary',
                    iconCls: 'icon-money',
                    layout: {
                        type:'fit',
                        align:'stretch',
                        pack:'start'
                    },
                    items: [employeeSalaryView]
                },{
                    title: 'Discipline',
                    iconCls: 'icon-hammer',
                    layout: {
                        type:'fit',
                        align:'stretch',
                        pack:'start'
                    },
                    items: [employeeDisciplineView]
                },{
                    title: 'Royal Decoration',
                    iconCls: 'icon-badge',
                    layout: {
                        type:'fit',
                        align:'stretch',
                        pack:'start'
                    },
                    items: [employeeDecorationView]
                },{
                    title: 'Date Specification',
                    iconCls: 'icon-calendar',
                    layout: {
                        type:'fit',
                        align:'stretch',
                        pack:'start'
                    },
                    items: [employeeDateView]
                },{
                    title: 'Address',
                    iconCls: 'icon-home',
                    layout: {
                        type:'fit',
                        align:'stretch',
                        pack:'start'
                    },
                    items: [employeeAddressView]
                },{
                    title: 'Family',
                    iconCls: 'icon-family',
                    layout: {
                        type:'fit',
                        align:'stretch',
                        pack:'start'
                    },
                    items: [employeeFamilyView]
                }]
            }]
        }]
    });