Merge pull request #3564 from Symbai/datagrid1

DataGrid - Fix remaining theme colors

src/Avalonia.Controls.DataGrid/Themes/Default.xaml

@@ -202,7 +202,7 @@
     <Setter Property="BorderThickness" Value="{DynamicResource ThemeBorderThickness}" />
     <Setter Property="DropLocationIndicatorTemplate">
       <Template>
-        <Rectangle Fill="#FF3F4346" Width="2"/>
+        <Rectangle Fill="{DynamicResource ThemeBorderHighColor}" Width="2"/>
       </Template>
     </Setter>
     <Setter Property="Template">
@@ -215,11 +215,11 @@
             <DataGridColumnHeader Name="PART_TopLeftCornerHeader" Width="22" />
             <DataGridColumnHeadersPresenter Name="PART_ColumnHeadersPresenter" Grid.Column="1"/>
             <DataGridColumnHeader Name="PART_TopRightCornerHeader" Grid.Column="2"/>
-            <Rectangle Name="PART_ColumnHeadersAndRowsSeparator" Grid.ColumnSpan="3" VerticalAlignment="Bottom" StrokeThickness="1" Height="1" Fill="#FFC9CACA"/>
+            <Rectangle Name="PART_ColumnHeadersAndRowsSeparator" Grid.ColumnSpan="3" VerticalAlignment="Bottom" StrokeThickness="1" Height="1" Fill="{DynamicResource ThemeControlMidHighBrush}"/>
 
             <DataGridRowsPresenter Name="PART_RowsPresenter" Grid.ColumnSpan="2" Grid.Row="1" />
-            <Rectangle Name="BottomRightCorner" Fill="#FFE9EEF4" Grid.Column="2" Grid.Row="2" />
-            <Rectangle Name="BottomLeftCorner" Fill="#FFE9EEF4" Grid.Row="2" Grid.ColumnSpan="2" />
+            <Rectangle Name="BottomRightCorner" Fill="{DynamicResource ThemeControlMidHighBrush}" Grid.Column="2" Grid.Row="2" />
+            <Rectangle Name="BottomLeftCorner" Fill="{DynamicResource ThemeControlMidHighBrush}" Grid.Row="2" Grid.ColumnSpan="2" />
             <ScrollBar Name="PART_VerticalScrollbar" Orientation="Vertical" Grid.Column="2" Grid.Row="1" Width="{DynamicResource ScrollBarThickness}"/>
 
             <Grid Grid.Column="1" Grid.Row="2"