UWP中設置CommandBar .SecondaryCommands的背景色

通過設置CommandBar的CommandBarOverflowPresenterStyle屬性，可以設置SecondaryCommands的樣式，其TargetType是CommandBarOverflowPresenter
樣例：

<Style TargetType="CommandBar">
    <Setter Property="Background" Value="{ThemeResource SolidColorBrushMainGridBackground}"></Setter>
    <Setter Property="CommandBarOverflowPresenterStyle">
        <Setter.Value>
            <Style TargetType="CommandBarOverflowPresenter">
                <Setter Property="Background" Value="{ThemeResource SolidColorBrushMainGridBackground}"></Setter>
            </Style>
        </Setter.Value>
    </Setter>
</Style>