How to add button to wpf datagridcomboboxcolumn

<DataGridTemplateColumn Header="Combo Style">
                    <DataGridTemplateColumn.CellTemplate>
                        <DataTemplate>
                            <StackPanel Orientation="Horizontal">
                                <ComboBox />
                                <Button />
                            </StackPanel>
                        </DataTemplate>
                    </DataGridTemplateColumn.CellTemplate>
                </DataGridTemplateColumn>