ux: add a check mark to indicate which side is HEAD in Compare window

Signed-off-by: leo <longshuang@msn.cn>

Author: love-linger

src/Views/Compare.axaml

@@ -48,7 +48,10 @@
                         User="{Binding BaseHead.Author}"/>
               <TextBlock Grid.Column="1" Text="{Binding BaseHead.Author.Name}" Margin="8,0,0,0"/>
               <Border Grid.Column="2" Background="{DynamicResource Brush.Accent}" CornerRadius="4">
-                <TextBlock Text="{Binding BaseName}" Margin="4,0" Foreground="#FFDDDDDD"/>
+                <StackPanel Orientation="Horizontal">
+                  <Path Width="12" Height="12" Margin="4,2,0,0" Data="{StaticResource Icons.Check}" Fill="White" IsVisible="{Binding BaseHead.IsCurrentHead, Mode=OneWay}"/>
+                  <TextBlock Text="{Binding BaseName}" Margin="4,0" Foreground="#FFDDDDDD"/>        
+                </StackPanel>
               </Border>
               <TextBlock Grid.Column="3" Text="{Binding BaseHead.SHA, Converter={x:Static c:StringConverters.ToShortSHA}}" Foreground="DarkOrange" Margin="8,0,0,0" TextDecorations="Underline" Cursor="Hand" PointerPressed="OnPressedSHA"/>
               <TextBlock Grid.Column="4" Text="{Binding BaseHead.CommitterTimeStr}" Foreground="{DynamicResource Brush.FG2}" Margin="8,0,0,0"/>
@@ -72,7 +75,10 @@
                         User="{Binding ToHead.Author}"/>
               <TextBlock Grid.Column="1" Text="{Binding ToHead.Author.Name}" Margin="8,0,0,0"/>
               <Border Grid.Column="2" Background="{DynamicResource Brush.Accent}" CornerRadius="4">
-                <TextBlock Text="{Binding ToName}" Margin="4,0" Foreground="#FFDDDDDD"/>
+                <StackPanel Orientation="Horizontal">
+                  <Path Width="12" Height="12" Margin="4,2,0,0" Data="{StaticResource Icons.Check}" Fill="White" IsVisible="{Binding ToHead.IsCurrentHead, Mode=OneWay}"/>
+                  <TextBlock Text="{Binding ToName}" Margin="4,0" Foreground="#FFDDDDDD"/>
+                </StackPanel>
               </Border>
               <TextBlock Grid.Column="3" Text="{Binding ToHead.SHA, Converter={x:Static c:StringConverters.ToShortSHA}}" Foreground="DarkOrange" Margin="8,0,0,0" TextDecorations="Underline" Cursor="Hand" PointerPressed="OnPressedSHA"/>
               <TextBlock Grid.Column="4" Text="{Binding ToHead.CommitterTimeStr}" Foreground="{DynamicResource Brush.FG2}" Margin="8,0,0,0"/>