<ComboBox Name="identifiercombo" Text="{Binding SelectedIdentifier, UpdateSourceTrigger=PropertyChanged}" ItemsSource="{Binding IdentifierCollection}" SelectedIndex="0" IsEditable="True" Grid.Row="3" Grid.Column="1" HorizontalAlignment="Stretch" Margin="10,5">
<ComboBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<CheckBox Click="CheckBox_Click" Content="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=Content,UpdateSourceTrigger=PropertyChanged}" VerticalAlignment="Center"/>
</StackPanel>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>