Question

I have the following code snippet (copy and paste into kaxaml, xamlpad, etc to try it)
that collapses all but the selected item. However, I want to revert back to all visible
when the mouse is not over the ListBox and I just cannot get it to work short of going code behind. I am using the IsMouseOver ListBox property to set selected item properties on the ListBox to attempt to trigger an update but no luck.
Any ideas?

<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
 <Grid>
      <ListBox
           Name="lb"
           Width="100"
           Height="100"
           Background="Red"
           SelectionMode="Single">
           <ListBox.ItemsPanel>
                <ItemsPanelTemplate>
                     <UniformGrid Columns="1"/>
                </ItemsPanelTemplate>
           </ListBox.ItemsPanel>
           <ListBoxItem Background="AliceBlue">Item 1    
           </ListBoxItem>
           <ListBoxItem Background="Aquamarine">Item 
           </ListBoxItem>
           <ListBoxItem Background="Azure">Item 
           </ListBoxItem>
           <ListBox.ItemContainerStyle>
                <Style TargetType="{x:Type ListBoxItem}">
                     <Setter Property="Visibility" Value="Visible"/>
                     <Style.Triggers>
                          <MultiDataTrigger>
                               <MultiDataTrigger.Conditions>
                                    <Condition Binding="{Binding RelativeSource={RelativeSource Self}, Path=IsSelected}" Value="False"/>
                                    <Condition Binding="{Binding RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type ListBox}},Path=SelectedItems.Count}" Value="1"/>
                               </MultiDataTrigger.Conditions>
                               <MultiDataTrigger.EnterActions>
                                    <BeginStoryboard>
                                         <Storyboard Duration="0:0:1">
                                              <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility">
                                                   <DiscreteObjectKeyFrame KeyTime="0:0:1" Value="{x:Static Visibility.Collapsed}"/>
                                              </ObjectAnimationUsingKeyFrames>
                                              <DoubleAnimation Duration="0:0:1" Storyboard.TargetProperty="Opacity" To="0"/>
                                         </Storyboard>
                                    </BeginStoryboard>
                               </MultiDataTrigger.EnterActions>
                          </MultiDataTrigger>
                          <MultiDataTrigger>
                               <MultiDataTrigger.Conditions>
                                    <Condition Binding="{Binding RelativeSource={RelativeSource Self}, Path=IsSelected}" Value="True"/>
                                    <Condition Binding="{Binding RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type ListBox}},Path=SelectedItems.Count}" Value="1"/>
                               </MultiDataTrigger.Conditions>
                               <MultiDataTrigger.EnterActions>
                                    <BeginStoryboard>
                                         <Storyboard Duration="0:0:0">
                                              <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility">
                                                   <DiscreteObjectKeyFrame KeyTime="0:0:0" Value="{x:Static Visibility.Visible}"/>
                                              </ObjectAnimationUsingKeyFrames>
                                              <DoubleAnimation Duration="0:0:0" Storyboard.TargetProperty="Opacity" To="1"/>
                                         </Storyboard>
                                    </BeginStoryboard>
                               </MultiDataTrigger.EnterActions>
                          </MultiDataTrigger>
                     </Style.Triggers>
                </Style>
           </ListBox.ItemContainerStyle>
           <ListBox.Style>
                <Style>
                     <Style.Triggers>
                          <Trigger Property="ListBox.IsMouseOver" Value="False">
                               <Setter Property="ListBox.SelectedItem" Value="{x:Null}"/>
                               <Setter Property="ListBoxItem.IsSelected" Value="False"/>
                               <Setter Property="ListBox.SelectedIndex" Value="-1"/>
                          </Trigger>
                          <EventTrigger RoutedEvent="Mouse.MouseLeave">
                               <BeginStoryboard>
                                    <Storyboard>
                                         <Int32Animation Duration="0:0:0" Storyboard.TargetProperty="SelectedIndex" To="-1"/>
                                    </Storyboard>
                               </BeginStoryboard>
                          </EventTrigger>
                     </Style.Triggers>
                </Style>
           </ListBox.Style>
      </ListBox>
 </Grid>
</Page>

Answer 1

Move your style to resources and apply it when the mouse is over the ListBox.`

<Page.Resources>
    <Style x:Key="CustomStyle" TargetType="{x:Type ListBoxItem}">
        <Style.Triggers>
            <MultiDataTrigger>
                <MultiDataTrigger.Conditions>
                    <Condition Binding="{Binding RelativeSource={RelativeSource Self}, Path=IsSelected}" Value="False"/>
                    <Condition Binding="{Binding RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type ListBox}},Path=SelectedItems.Count}" Value="1"/>
                </MultiDataTrigger.Conditions>
                <MultiDataTrigger.EnterActions>
                    <BeginStoryboard>
                        <Storyboard Duration="0:0:1">
                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility">
                                <DiscreteObjectKeyFrame KeyTime="0:0:1" Value="{x:Static Visibility.Collapsed}"/>
                            </ObjectAnimationUsingKeyFrames>
                            <DoubleAnimation Duration="0:0:1" Storyboard.TargetProperty="Opacity" To="0"/>
                        </Storyboard>
                    </BeginStoryboard>
                </MultiDataTrigger.EnterActions>
                <MultiDataTrigger.ExitActions>
                    <BeginStoryboard>
                        <Storyboard Duration="0:0:0">
                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility">
                                <DiscreteObjectKeyFrame KeyTime="0:0:0" Value="{x:Static Visibility.Visible}"/>
                            </ObjectAnimationUsingKeyFrames>
                            <DoubleAnimation Duration="0:0:0" Storyboard.TargetProperty="Opacity" To="1"/>
                        </Storyboard>
                    </BeginStoryboard>
                </MultiDataTrigger.ExitActions>
            </MultiDataTrigger>
        </Style.Triggers>
    </Style>
</Page.Resources>

<Grid>
    <ListBox
       Name="lb"
       Width="100"
       Height="100"
       Background="Red"
       SelectionMode="Single">
        <ListBox.ItemsPanel>
            <ItemsPanelTemplate>
                <UniformGrid Columns="1"/>
            </ItemsPanelTemplate>
        </ListBox.ItemsPanel>
        <ListBoxItem Background="AliceBlue">Item 1
        </ListBoxItem>
        <ListBoxItem Background="Aquamarine">Item
        </ListBoxItem>
        <ListBoxItem Background="Azure">Item
        </ListBoxItem>
        <ListBox.Style>
            <Style>
                <Style.Triggers>
                    <Trigger Property="ListBox.IsMouseOver" Value="True">
                        <Setter 
                            Property="ListBox.ItemContainerStyle" 
                            Value="{StaticResource CustomStyle}"/>
                    </Trigger>
                </Style.Triggers>
            </Style>
        </ListBox.Style>
    </ListBox>
</Grid>

`
Also note the usage of the MultiDataTrigger.ExitActions, these are the actions to apply when the trigger object becomes inactive.