DataGrid loses choice

Question

There is a set of product categories.

Each category is represented in the interface by the AvalonDock tab, which has a DataGrid with products.

Now, when switching from tab to tab, the DataGrid updates the collection every time. If you select a couple of rows in the table on the first tab, switch to the second tab and return to the first, the selection disappears.

What could be the problem?

XAML:

<xcad:DockingManager DocumentsSource="{Binding Examples}"> <xcad:DockingManager.LayoutItemTemplate> <DataTemplate> <ListBox ItemsSource="{Binding Content.Items}" SelectionMode="Extended" /> </DataTemplate> </xcad:DockingManager.LayoutItemTemplate> <xcad:LayoutRoot /> </xcad:DockingManager>> 

Code for:

 public partial class MainWindow : Window { public class Example { public List<int> Items { get; } = new List<int>(); public Example() { for (var i = 0; i < 10; i++) { Items.Add(i); } } } public List<Example> Examples { get; } = new List<Example>(); public MainWindow() { InitializeComponent(); DataContext = this; Examples.Add(new Example()); Examples.Add(new Example()); } } 

Answer 1

As @nobody suggested, switching between tabs seems to refresh the layout, and the selection state is lost. If the user interface cannot save the selection state, you can use the next level, such as a presentation or presentation model, to do the same.

In this case, adding the IsSelected property for the view-model element and binding to the ListViewItem should do the trick.

XAML:

 <Grid> <xcad:DockingManager DocumentsSource="{Binding Examples}"> <xcad:DockingManager.DocumentHeaderTemplate> <DataTemplate> <TextBlock Text="Doc" /> </DataTemplate> </xcad:DockingManager.DocumentHeaderTemplate> <xcad:DockingManager.LayoutItemTemplate> <DataTemplate> <ListBox DisplayMemberPath="Value" ItemsSource="{Binding Content.Items}" SelectionMode="Extended"> <ListBox.Resources> <SolidColorBrush x:Key="{x:Static SystemColors.InactiveSelectionHighlightBrushKey}" Color="LightBlue" /> <Style TargetType="{x:Type ListBoxItem}"> <Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay}" /> </Style> </ListBox.Resources> </ListBox> </DataTemplate> </xcad:DockingManager.LayoutItemTemplate> <xcad:LayoutRoot /> </xcad:DockingManager> </Grid> 

Code for:

 public partial class MainWindow : Window { public class ExampleItem { public int Value { get; set; } public bool IsSelected { get; set; } } public class Example { public List<ExampleItem> Items { get; } = new List<ExampleItem>(); public Example() { for (var i = 0; i < 10; i++) { Items.Add(new ExampleItem { Value = i }); } } } public List<Example> Examples { get; } = new List<Example>(); public MainWindow() { InitializeComponent(); DataContext = this; Examples.Add(new Example()); Examples.Add(new Example()); } }