Windows Phone 8 development - Change icon color depending on phone background

Smart way to change icon color:

<Border x:Name="Wifi" Width="76" Height="76" 
                    HorizontalAlignment="Right" VerticalAlignment="Bottom" 
                    Background="{StaticResource PhoneForegroundBrush}"                                Margin="0,0,360,82" Tap="WhenTappedWifi" >
        <Border.OpacityMask>
             <ImageBrush ImageSource="Assets/Tiles/Custom/wifi.png" />
        </Border.OpacityMask>
</Border>

Source: http://igrali.com/2012/01/21/make-image-visible-on-both-white-and-black-background-theme-color-on-windows-phone/