<Grid>
<Button HorizontalAlignment="Center"
VerticalAlignment="Center"
Content="Test">
<Button.Flyout>
<Flyout>
<Flyout.FlyoutPresenterStyle>
<Style TargetType="FlyoutPresenter">
<Setter Property="Background"
Value="White" />
<Setter Property="CornerRadius"
Value="20" />
<Setter Property="Padding"
Value="0" />
</Style>
</Flyout.FlyoutPresenterStyle>
<Border>
<TextBlock HorizontalAlignment="Center"
VerticalAlignment="Center"
Text="Shadow Test" />
</Border>
</Flyout>
</Button.Flyout>
</Button>
</Grid>