wpf - Custom styled listbox - how can I keep the style for a selected item?

Question

I have a styled listbox. Listbox items change color when hovered over and when selected. Hover and select work fine. But when selecting an item then taking the mouse off it and coming back to hover over it causes it to go back to hover/unselected state even though it is still selected. How can I keep the listboxitem in a "selected" visual state?

<Style x:Name="myListBoxItemStyle" TargetType="ListBoxItem">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="ListBoxItem">
                <Border x:Name="myBorder" CornerRadius="5" BorderThickness="3" Background="#FF292121" Margin="0">
                    <Grid HorizontalAlignment="Stretch">
                        <ContentPresenter Content="{TemplateBinding Content}" Margin="5,0,5,0" />
                    </Grid>
                    <VisualStateManager.VisualStateGroups>
                        <VisualStateGroup x:Name="CommonStates">
                            <VisualState x:Name="Normal"/>
                            <VisualState x:Name="MouseOver">
                                <Storyboard>
                                    <ColorAnimation Storyboard.TargetName="myBorder" Storyboard.TargetProperty="(Background).(SolidBrush.Color)" Duration="00:00:00.2" To="#FF949290" />
                                </Storyboard>
                            </VisualState>
                            <VisualState x:Name="Disabled"/>
                        </VisualStateGroup>
                        <VisualStateGroup x:Name="SelectionStates">
                            <VisualState x:Name="Unselected" />
                            <VisualState x:Name="Selected">
                                <Storyboard>
                                    <ColorAnimation Storyboard.TargetName="myBorder" Storyboard.TargetProperty="(Background).(SolidBrush.Color)" Duration="00:00:00.2" To="#FF949290" />
                                </Storyboard>
                            </VisualState>
                            <VisualState x:Name="SelectedUnfocused"/>
                        </VisualStateGroup>
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

<Style x:Key="myListBoxStyle" TargetType="ListBox">
    <Setter Property="Background" Value="Transparent"/>
    <Setter Property="Margin" Value="0"/>
    <Setter Property="BorderThickness" Value="0"/>
    <Setter Property="ItemContainerStyle" Value="{StaticResource myListBoxItemStyle}"/>
    <Setter Property="VerticalAlignment" Value="Bottom"/>
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="ListBox">
                <Grid Margin="0">
                    <ItemsPresenter />
                </Grid>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
    <Setter Property="ItemsPanel">
        <Setter.Value>
            <ItemsPanelTemplate>
                <StackPanel Orientation="Horizontal"/>
            </ItemsPanelTemplate>
        </Setter.Value>
    </Setter>
</Style>

<ListBox Name="theControl" Style="{StaticResource myListBoxStyle}" />

Answer 1

What happening is your states (selected and mousover) from different state groups compete for the same property (myBorders's Background). You will have to add another element (rectangle maybe) and change that elements background in one of the states.

In general you should not manipulate same property of the same element from states in different state groups. Visual state manager doesn't know how to handle this situation, since it doesn't know which state should take precedence.