我怎样才能改变一个MetroWindow的背景是什么?
<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:Controls="clr-namespace:MahApps.Metro.Controls;assembly=MahApps.Metro"
xmlns:Behaviours="clr-namespace:MahApps.Metro.Behaviours"
xmlns:Converters="clr-namespace:MahApps.Metro.Converters"
xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity">
<Style BasedOn="{StaticResource {x:Type Controls:MetroWindow}}" TargetType="Controls:MetroWindow">
<Setter Property="Background" Value="LightGray" />
<Setter Property="BorderBrush" Value="#FFB9B9B9" />
<Setter Property="BorderThickness" Value="0,1,0,0" />
</Style>