[WPF] ComboBox and ItemSource: add one empty row

Question

Hi,

I have a ComboBox, defined as:

<ComboBox Name="cmbTypeOfSchedule"

DataContext="{StaticResource DomainDataViewModel}"

ItemsSource="{Binding SchedTypes}"

DisplayMemberPath="Description"

Width="120">

I would insert, in head, an empty item or empty called "Select all".

So:

1) I defined a StaticResource:

<CollectionViewSource x:Key="SchedTypesWithEmptyItem" Source="{Binding SchedTypes}" />

2) Edit my Combobox as:

                            <ComboBox Name="cmbTypeOfSchedule"

                                        DataContext="{StaticResource DomainDataViewModel}"

                                        DisplayMemberPath="Description"

                                        Width="120">

                                <ComboBox.ItemsSource>

                                    <CompositeCollection>

                                        <ComboBoxItem Content="Select all" />

                                        <CollectionContainer Collection="{Binding Source={StaticResource SchedTypesWithEmptyItem}}" />

                                    </CompositeCollection>

                                </ComboBox.ItemsSource>

The problem: in the ComboBox I see only "Select all" and not other item from my Collection and when I select "Select all", it does not stay selected.

Thanks.