Xaml 更改弹出按钮（UWP）的背景色

我的页面上有一个弹出控件，我想更改它的背景色。我怎样才能做到这一点

 <Button x:Name="btn"  Background="Transparent">
            <Image HorizontalAlignment="Center" />
            <Button.Flyout  >
                <Flyout Placement="Left" >
                    <ListView  ItemsSource="{x:Bind DDLItemsSource, Mode=OneWay}" Background="Green" VerticalAlignment="Stretch"  
                               SelectionChanged="StudentsList_SelectionChanged" x:Name="StudentsList" SelectionMode="Extended"  HorizontalAlignment="Stretch"  >
                        <Style TargetType="ListViewItem">
                            <Setter Property="HorizontalContentAlignment" Value="Stretch"/>
                        </Style>
                    </ListView>
                </Flyout>
            </Button.Flyout>
        </Button>

若我为子元素提供背景，它会在弹出型按钮和子元素之间提供一个边距，所以这是不可接受的。现在看起来像这样

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要更改弹出型按钮的背景色，可以尝试设置显示弹出型按钮内容的内部按钮的属性样式。例如：

<Button.Flyout>
    <Flyout Placement="Left">

        <Flyout.FlyoutPresenterStyle>
            <Style TargetType="FlyoutPresenter">
                <Setter Property="Background" Value="Green"/>
            </Style>
        </Flyout.FlyoutPresenterStyle>

        <ListView ItemsSource="{x:Bind DDLItemsSource, Mode=OneWay}" Background="Green" VerticalAlignment="Stretch"  SelectionChanged="StudentsList_SelectionChanged" x:Name="StudentsList" SelectionMode="Extended"  HorizontalAlignment="Stretch"  >
            <Style TargetType="ListViewItem">
                <Setter Property="HorizontalContentAlignment" Value="Stretch"/>
            </Style>
        </ListView>
    </Flyout>
</Button.Flyout>

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您需要一个自定义菜单OutPresenterStyle；参见上的示例