WPF

Bernhard Hiller wrote:

A CheckBox is an interactive element

BackgroundWorker worker = new BackgroundWorker();
//the action to run
worker.DoWork += (s, ev) =>
    {
        this.Dispatcher.Invoke(new Action(() =>
            UIHelper.ProgressBarRun(true)));

        context.Units.Load();
        context.UnitTypes.Load();
        unitNames = new ObservableCollection<UnitName>(
            context.Units.Local.Select(f => new UnitName() { Id = f.Id, Name = f.Name }));
    };
//what to run when the above completes
worker.RunWorkerCompleted += (s, ev) =>
    {
        viewSource.Source = context.Units.Local;
        unitTypeIdComboBox.ItemsSource = context.UnitTypes.Local;

        businessAreaIdComboBox.ItemsSource = unitNames;
        divisionalUnitIdComboBox.ItemsSource = unitNames;
        parentUnitIdComboBox.ItemsSource = unitNames;

        this.Dispatcher.Invoke(new Action(() =>
            {
                UIHelper.ProgressBarRun(false);
                navFirstButton.RaiseEvent(new RoutedEventArgs(Button.ClickEvent));
            }));
    };
//start the background work
worker.RunWorkerAsync();

<Page.Resources>
        <CollectionViewSource x:Key="unitViewSource"
                              Source="{Binding}" />
        <CollectionViewSource x:Key="unitsServicesViewSource"
                              Source="{Binding Path=Services, Source={StaticResource unitViewSource}}" />
        <CollectionViewSource x:Key="unitTypeViewSource"
                              d:DesignSource="{d:DesignData Source=/SampleData/UnitTypeSampleData.xaml}" />
        <CollectionViewSource x:Key="unitNameViewSource" />

<ComboBox Grid.Column="1"
          Grid.Row="1"
          Margin="3"
          Name="businessAreaIdComboBox"
          DisplayMemberPath="Name"
          SelectedValuePath="Id"
          SelectedItem="{Binding Path=BusinessArea}"
          ItemsSource="{Binding Source={StaticResource unitNameViewSource}}">
    <ComboBox.ItemsPanel>
        <ItemsPanelTemplate>
            <VirtualizingStackPanel />
        </ItemsPanelTemplate>
    </ComboBox.ItemsPanel>
    <ComboBox.InputBindings>
        <KeyBinding Key="Delete"
                    Command="{Binding RelativeSource={RelativeSource AncestorType=Page}, Path=ClearComboBoxCommand}"
                    CommandParameter="{Binding RelativeSource={RelativeSource AncestorType=ComboBox}, Path=Name}" />
    </ComboBox.InputBindings>
</ComboBox>

private void Page_Loaded(object sender, RoutedEventArgs e)
{
    //get the CollectionViewSource object
    viewSource = ((CollectionViewSource) (this.FindResource("unitViewSource")));

    try
    {
        //asynchronous
        BackgroundWorker worker = new BackgroundWorker();
        //the action to run
        worker.DoWork += (s, ev) =>
            {
                this.Dispatcher.Invoke(new Action(() =>
                    {
                        UIHelper.ProgressBarRun(true);
                        this.IsEnabled = false;
                    }));

                context.Units.Load();
                context.UnitTypes.Load();
            };
        //what to run when the above completes
        worker.RunWorkerCompleted += (s, ev) =>
            {
                viewSource.Source = context.Units.Local;
                unitTypeIdComboBox.ItemsSource = context.UnitTypes.Local;

                UpdateComboBoxes();

                this.Dispatcher.Invoke(new Action(() =>
                    {
                        UIHelper.ProgressBarRun(false);
                        navFirstButton.RaiseEvent(new RoutedEventArgs(Button.ClickEvent));
                        this.IsEnabled = true;
                    }));
            };
        //start the background work
        worker.RunWorkerAsync();

    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.Message);
    }
}

private void UpdateComboBoxes()
{
    var unitNames = context.Units.Local;
    businessAreaIdComboBox.ItemsSource = unitNames;
    divisionalUnitIdComboBox.ItemsSource = unitNames;
    parentUnitIdComboBox.ItemsSource = unitNames;
}