Combobox in ListTreeView

Hi,

I'm new to WPF and ActiPro. Is this the proper way of making combobox columns for a ListTreeView?

                                   <grids:TreeListView x:Name="treeListView" 
                                                        RootItem="{Binding Path=RootItem, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
                                                        SelectedItem="{Binding Path=SelectedItem, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
                                                        TopLevelIndent="0">
                                        <grids:TreeListView.ItemAdapter>
                                            <OutboardEditorVariables:DefaultTreeListBoxItemAdapter ChildrenBinding="{Binding Children}" ChildrenPath="Children" />
                                        </grids:TreeListView.ItemAdapter>
                                        <grids:TreeListView.Columns>
                                            <grids:TreeListViewColumn Header="Type" Width="*" HeaderHorizontalAlignment="Left" CellHorizontalAlignment="Stretch">
                                                <DataTemplate>
                                                    <ComboBox SelectedItem="{Binding SelectedType}" Width="Auto" Style="{StaticResource comboBoxDefaultStyle}" 
                                                              ItemsSource="{Binding OriginTypes}"/>
                                                </DataTemplate>
                                            </grids:TreeListViewColumn>
                                            <grids:TreeListViewColumn Header="Name" Width="*" HeaderHorizontalAlignment="Left" CellHorizontalAlignment="Stretch" >
                                                <DataTemplate>
                                                    <ComboBox Style="{StaticResource comboBoxDefaultStyle}" ItemsSource="{Binding Names}"/>
                                                </DataTemplate>
                                            </grids:TreeListViewColumn>
                                            <grids:TreeListViewColumn Header="Parameter" Width="*" HeaderHorizontalAlignment="Left" CellHorizontalAlignment="Stretch">
                                                <DataTemplate>
                                                    <ComboBox Style="{StaticResource comboBoxDefaultStyle}" ItemsSource="{Binding Parameters}"/>
                                                </DataTemplate>
                                            </grids:TreeListViewColumn>
                                        </grids:TreeListView.Columns>
                                    </grids:TreeListView>

It works but the combobox is not fully stretched