当您重新设置DataGridCell的模板时,也会丢失实际上是绘制背景的控件的边框。加上这个就行了。
<Style TargetType="{x:Type DataGridCell}">
<Style.Triggers>
<Trigger Property="IsSelected" Value="True">
<Setter Property="Background" Value="Red"/>
</Trigger>
</Style.Triggers>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type DataGridCell}">
<Border Background="{TemplateBinding Background}">
<ContentPresenter VerticalAlignment="Center"></ContentPresenter>
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>