How to use the traitsui.api.VGroup function in traitsui

def traits_view(self):
        commit_grp = VGroup(Item('ncommits', label='Limit'),
                            VGroup(UItem('commits',
                                         editor=TabularEditor(adapter=CommitAdapter(),
                                                              selected='selected_commit')),
                                   show_border=True, label='Commits'))
        bookmark_grp = VGroup(VGroup(UItem('git_tags', editor=TabularEditor(adapter=GitTagAdapter()),
                                           height=200),
                                     show_border=True, label='Bookmarks'))

        v = View(VGroup(UItem('branch',
                              editor=EnumEditor(name='branches')),
                        VSplit(commit_grp, bookmark_grp)))
        return v

),
                Item('case_sensitive')
            ),
            VSplit(
                VGroup(
                    Item('summary',
                         editor=TitleEditor()
                         ),
                    Item('source_files',
                         id='source_files',
                         editor=table_editor
                         ),
                    dock='horizontal',
                    show_labels=False
                ),
                VGroup(
                    HGroup(
                        Item('selected_full_name',
                             editor=TitleEditor(),
                             springy=True
                             ),
                        Item('selected_full_name',
                             editor=DNDEditor(),
                             tooltip='Drag this file'
                             ),
                        show_labels=False
                    ),
                    Item('selected_contents',
                         style='readonly',
                         editor=CodeEditor(mark_lines='mark_lines',
                                           line='selected_line',
                                           selected_line='selected_line')

callee_map = Dict()

    # Map from the (file, lineno, name) tuple to the record.
    record_map = Dict()


    #### GUI traits ############################################################

    basenames = Bool(True)
    percentages = Bool(True)
    filename = Str()
    line = Int(1)
    code = Str()

    traits_view = tui.View(
        tui.VGroup(
            tui.HGroup(
                tui.Item('basenames'),
                tui.Item('percentages'),
            ),
            tui.HGroup(
                tui.UItem('main_results'),
                tui.VGroup(
                    tui.Label('Callees'),
                    tui.UItem('callee_results'),
                    tui.Label('Callers'),
                    tui.UItem('caller_results'),
                    tui.UItem('filename', style='readonly'),
                    tui.UItem('code', editor=tui.CodeEditor(line='line')),
                ),
                style='custom',
            ),

Item('streamline_param', label="DTB_streamline Parameters"),
               show_border = True,
               visible_when = "diffusion_imaging_model == 'DSI' or diffusion_imaging_model == 'QBALL'",
            ),
        VGroup(
               Item('streamline_param', label="DTB_streamline Parameters"),
               show_border = True,
               visible_when = "diffusion_imaging_model == 'DTI'"   
            ),
        enabled_when = "active_tractography",
        visible_when = "active_tractography",
        label = "Tractography",                         
        )
    
    fiberfilter_group = Group(
        VGroup(
               Item('apply_splinefilter', label="Apply spline filter"),
               Item('apply_fiberlength', label="Apply cutoff filter"),
               Item('fiber_cutoff_lower', label='Lower cutoff length (mm)', enabled_when = 'apply_fiberlength'),
               Item('fiber_cutoff_upper', label='Upper cutoff length (mm)', enabled_when = 'apply_fiberlength'),
               show_border = True,
               enabled_when = "active_fiberfilter"   
            ),
        visible_when = "active_fiberfilter",
        label = "Fiber Filtering",                         
        )

    applyregistration_group = Group(
        VGroup(
               Item('parcellation_scheme', label="Used Parcellation Scheme"),
               show_border = True,
               enabled_when = "active_applyregistration"

return View(VGroup(Item('controls_list',
                                editor = VerticalListEditor(editor = InstanceEditor(view = self.control_traits_view()),
                                                            style = 'custom',
                                                            mutable = False),
                                style = 'custom'),
                    Item('handler.add_control',
                         editor = ButtonEditor(value = True,
                                               label = "Add a control")),
                    Item('handler.remove_control',
                         editor = ButtonEditor(value = True,
                                               label = "Remove a control")),
                    label = "Controls",
                    show_labels = False),
                    Item('mixture_model',
                         label = "Use mixture\nmodel?"),
                    VGroup(Item('subset_list',
                                show_label = False,
                                editor = SubsetListEditor(conditions = "context.previous_wi.conditions",
                                                          metadata = "context.previous_wi.metadata",
                                                          when = "'experiment' not in vars() or not experiment")),
                           label = "Subset",
                           show_border = False,
                           show_labels = False),
                    Item('do_estimate',
                         editor = ButtonEditor(value = True,
                                               label = "Estimate!"),
                         show_label = False),
                    shared_op_traits)

def traits_view(self):
        # style_sheet='QLabel {font-size: 10px} QLineEdit {font-size: 10px}'

        a = VGroup(UItem('value'),
                   UItem('error_message', style='readonly', style_sheet=STYLESHEET))
        buttons = [OKButton(), 'Cancel']
        return self._new_view(a,
                              width=400,
                              title='Add {}'.format(self.tag),
                              buttons=buttons)

def _define_task_view(self):
        """
        """
        line_completer = LineCompleterEditor(
                             entries_updater = self._list_database_entries)
        view = View(
                    VGroup(
                        UItem('task_name', style = 'readonly'),
                        Group(
                            Label('Array'), Label('Column name'),
                            Label('Mode'),
                            UItem('target_array', editor = line_completer),
                            UItem('column_name'),
                            UItem('mode'),
                            columns = 3,
                            show_border = True,
                            ),
                        ),
                     )

        self.trait_view('task_view', view)

def traits_view(self):
        required_grp = VGroup(Item('sample_type', label='Sample Type'),
                              Item('name', label='Name'),
                              Item('material', label='Material'),
                              label='Required', show_border=True)

        collection_grp = VGroup(Item('collector', label='Collection'),
                                Item('collection_method', label='Collection Method'),
                                HGroup(Item('_collection_start_date', label='Collection Start Date'),
                                       UItem('_collection_start_time'),
                                       UItem('timezone')),
                                label='Collection')
        location_grp = VGroup(Item('latitude', label='Latitude', tooltip=LAT_TT),
                              Item('longitude', label='Longitude', tooltip=LONG_TT),
                              Item('elevation', label='Elevation', tooltip=ELEVATION_TT),
                              Item('primary_location_name', label='Primary Location Name'),
                              Item('country', label='Country'),
                              Item('province', label='State/Province'),

def current_state_view(self):
        g = VGroup(Item('graph', show_label=False, style='custom'),
                   VGroup(Item('scan_func', label='Function', style='readonly'),

                          HGroup(Item('scan_period', label='Period ({})'.format(self.scan_units)), spring),
                          Item('current_scan_value', style='readonly')),
                   VGroup(
                       HGroup(Item('scan_button', editor=ButtonEditor(label_value='scan_label'),
                                   show_label=False),
                              spring),
                       Item('scan_root',
                            style='readonly',
                            label='Scan directory',
                            visible_when='object.record_scan_data'),
                       Item('scan_name', label='Scan name',
                            style='readonly',
                            visible_when='object.record_scan_data'),
                       visible_when='object.is_scanable'),

def traits_view(self):
        v = View(VGroup(
                        HGroup(spring, CustomLabel('name', color='maroon', size=16,
                                                   height=-25,
                                                   width=100,
                                                   ), spring),
                        Item('container', show_label=False, editor=ComponentEditor()),
                 ))
        return v