wpf listbox resetting selectedIndex when containing grid resizes - wpf

Question

I need a composite view consisting of a top part that can be hidden, a bottom part consisting of a navigation menu (listbox) on the left and a content area on the right.
One option in the listbox should make the top-part collapsed and other listoptions should show the top-part.
My idea was to split the screen in top- and bottom part using a grid with three rows (middle row for gridsplitter) and currently Im using codebehind for changing the height of the top grid.
The Problem is that when I set the Grid.Height-prop from codebehind, my ListBox.SelectedIndex is set from 1 to 0 ! Thing is that if I change order of the two menu-items, it works fine!
We are using Caliburn Micro, but I don't think that changes anything - the example could be implemented with INotifyPropertyChanged as well.
<UserControl x:Uid="UserControl_1" x:Class="VisionAir.Client.Gui.Common.Windows.Foo.Views.BarView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d" Height="300" Width="300">
<UserControl.Resources>
<ResourceDictionary>
<BooleanToVisibilityConverter x:Key="BoolToVisConverter"/>
</ResourceDictionary>
</UserControl.Resources>
<Grid Name="ResizableGrid">
<Grid.RowDefinitions>
<RowDefinition Height="100" Name="TopRow"/>
<RowDefinition Height="10" Name="SplitterRow"/>
<RowDefinition Name="BottomRow"/>
</Grid.RowDefinitions>
<Grid Grid.Row="0" Name="TopRowGrid" Background="Chartreuse" Visibility="{Binding ShowSearchView, Converter={StaticResource BoolToVisConverter}}"/>
<GridSplitter Grid.Row="1" Visibility="{Binding ShowSearchView,Converter={StaticResource BoolToVisConverter}}" ResizeBehavior="PreviousAndCurrent" HorizontalAlignment="Stretch" Height="10"/>
<Grid Name="ListGrid" Grid.Row="2">
<Grid.ColumnDefinitions>
<ColumnDefinition/>
<ColumnDefinition/>
</Grid.ColumnDefinitions>
<ListBox Grid.Column="0" ItemsSource="{Binding Items}" SelectedIndex="{Binding SelectedIndex}" DisplayMemberPath="DisplayName">
</ListBox>
<Grid Background="Chocolate" Grid.Column="1"/>
</Grid>
<Canvas Name="FooCanvas" Visibility="{Binding ShowSearchView, Converter={StaticResource BoolToVisConverter}}"></Canvas>
</Grid>
</UserControl>
using System.Windows;
using System.Windows.Controls;
namespace VisionAir.Client.Gui.Common.Windows.Foo.Views
{
/// <summary>
/// Interaction logic for BarView.xaml
/// </summary>
public partial class BarView : UserControl
{
public BarView()
{
InitializeComponent();
FooCanvas.IsVisibleChanged += FooCanvas_IsVisibleChanged;
}
void FooCanvas_IsVisibleChanged(object sender, DependencyPropertyChangedEventArgs e)
{
bool isVisible = (bool)e.NewValue;
if (isVisible)
{
TopRow.Height = new GridLength(100);
SplitterRow.Height = new GridLength(0, GridUnitType.Auto);
}
else
{
TopRow.Height = new GridLength(0, GridUnitType.Auto);
SplitterRow.Height = new GridLength(0);
}
}
}
}
using System.Collections.Generic;
using Caliburn.Micro;
namespace VisionAir.Client.Gui.Common.Windows.Foo.ViewModels
{
public class BarViewModel : PropertyChangedBase
{
private List<Screen> _items = new List<Screen>();
public BarViewModel()
{
Items.Add(new Screen() { DisplayName = "Hide" });
Items.Add(new Screen() { DisplayName = "Show" });
}
public bool ShowSearchView { get { return SelectedIndex == 1; } }
private int _selectedIndex;
public List<Screen> Items
{
get { return _items; }
set { _items = value; }
}
public int SelectedIndex
{
get { return _selectedIndex; }
set
{
System.Diagnostics.Debug.WriteLine(value);
_selectedIndex = value;
NotifyOfPropertyChange(() => ShowSearchView);
}
}
}
}