WPF ListBox items with template become invisible after grouping - wpf

Question

I have ObservableCollection with items which I want to display in a ListBox.
Also I write a template for ListboxItem for correct display of my collection.
On this stage everything works fine.
in .cs
Sensors = new ObservableCollection<Sensor>();
...
lstBox.ItemsSource = Sensors;
in .xaml
...
<DataTemplate x:Key="SensorTileTemplate">
<Border>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="*"></RowDefinition>
<RowDefinition Height="*"></RowDefinition>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="70"></ColumnDefinition>
<ColumnDefinition Width="*"></ColumnDefinition>
<ColumnDefinition Width="*"></ColumnDefinition>
</Grid.ColumnDefinitions>
<TextBlock Text="{Binding Name}" Grid.Row="0" Grid.ColumnSpan="3"></TextBlock>
<Image Source="{Binding ImageModel.ImgSource}" Style="{StaticResource ImageGlowStyle}" Height="72" Grid.Row="1" Grid.Column="0"></Image>
<StackPanel Grid.Row="1" Grid.Column="1" Margin="5">
<TextBlock Text="IP:"></TextBlock>
<TextBlock Text="Port:"></TextBlock>
<TextBlock Text="Command port:"></TextBlock>
</StackPanel>
<StackPanel Grid.Row="1" Grid.Column="2" Margin="5">
<TextBlock Text="{Binding DeviceAddress}"></TextBlock>
<TextBlock Text="{Binding DeviceDataPort}"></TextBlock>
<TextBlock Text="{Binding DeviceControlPort}"></TextBlock>
</StackPanel>
</Grid>
</Border>
</DataTemplate>
<Style x:Key="ContainerStyle">
<Style.Triggers>
<DataTrigger Binding="{Binding IsSelected}" Value="True">
<Setter Property="ListBoxItem.Visibility" Value="Collapsed"/>
</DataTrigger>
</Style.Triggers>
</Style>
...
<ListBox Name="lstBox" Focusable="False"
SelectionChanged="lstBox_SelectionChanged"
HorizontalContentAlignment="Stretch"
ItemTemplate="{StaticResource SensorTileTemplate}"
ItemContainerStyle="{StaticResource ContainerStyle}">
</ListBox>
The problem appears when I need to group certain items using expander as a group container.
in .cs
...
ICollectionView view = CollectionViewSource.GetDefaultView(Sensors);
view.GroupDescriptions.Add(new PropertyGroupDescription("GroupNumber"));
lstBox.ItemsSource = view;
...
in .xaml
<!--Same Template and Style-->
...
...
<Style x:Key="GroupContainerStyle" TargetType="{x:Type GroupItem}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type GroupItem}">
<Expander IsExpanded="True">
<Expander.Header>
<StackPanel Orientation="Horizontal">
<TextBlock Text="Group #" />
<TextBlock Text="{Binding Name}" />
</StackPanel>
</Expander.Header>
<Expander.Content>
<ItemsPresenter />
</Expander.Content>
</Expander>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
...
<ListBox Name="lstBox" Focusable="False"
SelectionChanged="lstBox_SelectionChanged"
HorizontalContentAlignment="Stretch"
ItemTemplate="{StaticResource SensorTileTemplate}"
ItemContainerStyle="{StaticResource ContainerStyle}">
<ListBox.GroupStyle>
<GroupStyle ContainerStyle="{StaticResource GroupContainerStyle}" />
</ListBox.GroupStyle>
</ListBox>
This code works and groups items but items become invisible.
So without grouping items display correctly but with grouping expanders show nothing in it.
I think there is something about ItemsPresenter in Expander but can't figure out what.

Answer 1

The problem was in one third party theme I use in my app. That theme has a ListBox template like:
<Style TargetType="{x:Type ListBox}">
...
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ListBox}">
<Grid>
<Border x:Name="Border" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" CornerRadius="2" Background="{DynamicResource ControlBackgroundBrush}" />
<ScrollViewer Margin="1" Style="{DynamicResource NuclearScrollViewer}" Focusable="false" Background="{x:Null}">
<StackPanel Margin="1,1,1,1" IsItemsHost="true" />
</ScrollViewer>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Background" Value="{DynamicResource DisabledBackgroundBrush}" TargetName="Border" />
<Setter Property="BorderBrush" Value="{DynamicResource DisabledBorderBrush}" TargetName="Border" />
</Trigger>
<Trigger Property="IsGrouping" Value="true">
<Setter Property="ScrollViewer.CanContentScroll" Value="false" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
So I use an ItemsPresenter instead of the StackPanel in that template and everything works now.