Make DataGridCell BorderRadius and DataGridColumnHeader.Background configable.

src/Shared/HandyControl_Shared/Themes/Styles/DataGrid.xaml

@@ -47,10 +47,11 @@
         <Setter Property="HorizontalContentAlignment" Value="Left"/>
         <Setter Property="Padding" Value="{StaticResource DefaultControlPadding}"/>
         <Setter Property="Margin" Value="0,0,4,0"/>
+        <Setter Property="hc:BorderElement.CornerRadius" Value="4" />
         <Setter Property="Template">
             <Setter.Value>
                 <ControlTemplate TargetType="DataGridCell">
-                    <Border CornerRadius="4" Padding="{TemplateBinding Padding}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" SnapsToDevicePixels="True">
+                    <Border CornerRadius="{Binding Path=(hc:BorderElement.CornerRadius), RelativeSource={RelativeSource Mode=TemplatedParent}}" Padding="{TemplateBinding Padding}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" SnapsToDevicePixels="True">
                         <ContentPresenter HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                     </Border>
                 </ControlTemplate>
@@ -167,13 +168,14 @@
     <Style x:Key="DataGridColumnHeaderStyle" TargetType="DataGridColumnHeader">
         <Setter Property="VerticalContentAlignment" Value="Center"/>
         <Setter Property="Foreground" Value="{DynamicResource PrimaryTextBrush}"/>
+        <Setter Property="Background" Value="Transparent" />
         <Setter Property="Padding" Value="12,6,12,12"/>
         <Setter Property="MinHeight" Value="44"/>
         <Setter Property="Template">
             <Setter.Value>
                 <ControlTemplate TargetType="DataGridColumnHeader">
                     <hc:SimplePanel>
-                        <Border BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="Transparent" Padding="{TemplateBinding Padding}">
+                        <Border BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Padding="{TemplateBinding Padding}">
                             <Grid HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}">
                                 <Grid.ColumnDefinitions>
                                     <ColumnDefinition/>