Update simple theme caption buttons.

src/Avalonia.Themes.Simple/Controls/CaptionButtons.xaml

@@ -54,7 +54,8 @@
             </Viewbox>
           </Button>
           <Button x:Name="PART_MinimiseButton"
-                  Theme="{StaticResource SimpleCaptionButton}">
+                  Theme="{StaticResource SimpleCaptionButton}"
+                  AutomationProperties.Name="Minimise">
             <Viewbox Width="11"
                      Margin="2">
               <Path Data="M2048 1229v-205h-2048v205h2048z"
@@ -63,7 +64,8 @@
             </Viewbox>
           </Button>
           <Button x:Name="PART_RestoreButton"
-                  Theme="{StaticResource SimpleCaptionButton}">
+                  Theme="{StaticResource SimpleCaptionButton}"
+                  AutomationProperties.Name="Maximise">
             <Viewbox Width="11"
                      Margin="2">
               <Viewbox.RenderTransform>
@@ -78,7 +80,8 @@
           <Button x:Name="PART_CloseButton"
                   Background="#ffe81123"
                   BorderBrush="#fff1707a"
-                  Theme="{StaticResource SimpleCaptionButton}">
+                  Theme="{StaticResource SimpleCaptionButton}"
+                  AutomationProperties.Name="Close">
             <Viewbox Width="11"
                      Margin="2">
               <Path Data="M1169 1024l879 -879l-145 -145l-879 879l-879 -879l-145 145l879 879l-879 879l145 145l879 -879l879 879l145 -145z"
@@ -102,5 +105,8 @@
     <Style Selector="^:fullscreen /template/ Button#PART_MinimiseButton">
       <Setter Property="IsVisible" Value="False" />
     </Style>
+    <Style Selector="^ /template/ Button#PART_RestoreButton:disabled">
+      <Setter Property="Opacity" Value="0.2"/>
+    </Style>
   </ControlTheme>
 </ResourceDictionary>