Dynamic Resource: SystemColors.InactiveCaptionBrushKey

   
       

<StackPanel xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
            xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
            Background="{DynamicResource {x:Static SystemColors.InactiveCaptionBrushKey}}">

    <StackPanel.Resources> 
        <LinearGradientBrush x:Key="dynabrush1" StartPoint="0 0" EndPoint="1 1">
            <LinearGradientBrush.GradientStops>
                <GradientStop Offset="0" Color="{DynamicResource {x:Static SystemColors.ActiveCaptionColorKey}}" />
                <GradientStop Offset="1" Color="{DynamicResource {x:Static SystemColors.InactiveCaptionColorKey}}" />
            </LinearGradientBrush.GradientStops>
        </LinearGradientBrush>
        <SolidColorBrush x:Key="dynabrush2" Color="{DynamicResource {x:Static SystemColors.ActiveCaptionColorKey}}" />
    </StackPanel.Resources>
    <Label HorizontalAlignment="Center"
           FontSize="96"
           Content="Dynamic Resources"
           Background="{StaticResource dynabrush1}"
           Foreground="{StaticResource dynabrush2}" />

</StackPanel>