WPF: Trigger for ListBoxItem.IsSelected not working for Background property

Question

I try to change the Background property for my ListBoxItems using triggers in the ItemContainerStyle of my ListBox as fol

Answer 1

delete IsSelected trigger And add to listbox:

<ListBox.Resources>
    <SolidColorBrush x:Key="{x:Static SystemColors.HighlightBrushKey}"
                         Color="Red" />
    <SolidColorBrush x:Key="{x:Static SystemColors.ControlBrushKey}"
                         Color="Red" />
</ListBox.Resources>

First brush for focused second for otherwise

Answer 2

A little bit of reflecting on the Aero-style offers us an explanation to why this simple trigger-setting doesn't work.

The ListBoxItem has a ControlTemplate with triggers that takes precedence over our trigger. At least this seems to be true for a MultiTrigger. I´ve managed to override the simple trigger of Selected=true but for the multitrigger I had to make my own ControlTemplate.

This is the template from the Aero style that shows the problematic MultiTrigger:

<ControlTemplate TargetType="{x:Type ListBoxItem}">
    <ControlTemplate.Triggers>
        <Trigger Property="IsSelected" Value="true">
            <Setter TargetName="Bd" Value="{DynamicResource {x:Static HighlightBrush}}" Property="Background" />
            <Setter Value="{DynamicResource {x:Static HighlightTextBrush}}" Property="Foreground" />
        </Trigger>
        <MultiTrigger>
            <MultiTrigger.Conditions>
                <Condition Property="IsSelected" Value="true" />
                <Condition Property="IsSelectionActive" Value="false" />
            </MultiTrigger.Conditions>
            <Setter TargetName="Bd" Value="{DynamicResource {x:Static ControlBrush}}" Property="Background" />
            <Setter Value="{DynamicResource {x:Static ControlTextBrush}}" Property="Foreground" />
        </MultiTrigger>
        <Trigger Property="IsEnabled" Value="false">
            <Setter Value="{DynamicResource {x:Static GrayTextBrush}}" Property="Foreground" />
        </Trigger>
    </ControlTemplate.Triggers>
    <Border Name="Bd" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Padding="{TemplateBinding Padding}" SnapsToDevicePixels="true">
        <ContentPresenter HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
    </Border>
</ControlTemplate>

Hope it clears things up a little bit. I can't fathom why they´ve overcomplicated the style this much.

Answer 3

Try using Selector.IsSelected in your Trigger rather than IsSelected.

Answer 4

Try adding this to your window resources -

 <Window.Resources>
            <SolidColorBrush x:Key="{x:Static SystemColors.HighlightBrushKey}"
                             Color="Red" />
 </Window.Resources>

And remove the IsSelected Trigger from your code, it won't work because every system has its default highlight brush depending on your system theme.

You need to override the highlight brush in your code to make it work.