Sony Mobile will launch the SCR30 Style Cover Window case for the Xperia Z4 when it is released later this year. The Style Cover Window is a waterproof case (IPX5/8 classification) which has a window allowing you to activate a number of tasks without opening the cover including reading a message, controlling music, answering a call or activating the camera. The SCR30 case is made from PU leather and will be available in four colours (Black, White, Copper, Aqua).
To prepare for the launch, Sony has updated its Xperia wallpaper themes for three colours (Black, White and Copper) to match the case you may end up buying when the Xperia Z4 launches. This includes new wallpaper for these colours. Links to all can be found below.
Update: Sony Mobile has now launched the Aqua Green Xperia Z4 Style Cover Window Xperia Theme.
Thanks Abdoul and Ayub!