Update ListBox.xaml

src/Avalonia.Themes.Default/ListBox.xaml

@@ -1,4 +1,5 @@
-<Style xmlns="https://github.com/avaloniaui" Selector="ListBox">
+<Styles xmlns="https://github.com/avaloniaui" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
+    <Style Selector="ListBox">
   <Setter Property="Background" Value="{DynamicResource ThemeBackgroundBrush}"/>
   <Setter Property="BorderBrush" Value="{DynamicResource ThemeBorderMidBrush}"/>
   <Setter Property="BorderThickness" Value="{DynamicResource ThemeBorderThickness}"/>
@@ -23,7 +24,8 @@
       </Border>
     </ControlTemplate>
   </Setter>
-    <Style Selector="ComboBox:disabled /template/ Border#border">
+    </Style>
+    <Style Selector="ListBox:disabled /template/ Border#border">
         <Setter Property="Opacity" Value="{DynamicResource ThemeDisabledOpacity}" />
     </Style>
-</Style>
+</Styles>