I’ve used a semi-transparent AppBar on windows phone a number of times to get the visual effect I wanted and to stop the dreaded jumping frame when transitioning pages but I didn’t think it would be possible with the SysTray. Turns out that the SysTray in Windows Phone can be made transparent.
This is pretty useful if you want to keep an image background that spans the entire height of the screen. Simply add the attributes below to your root PhoneApplicationPage element.
shell:SystemTray.IsVisible="True" shell:SystemTray.ForegroundColor="Yellow" shell:SystemTray.Opacity="0"
and the result should look like this: