WhatsApp for Windows Phone might receive these nifty new features via an upcoming update12
A notable new perk, recently added to the private version of WhatsApp, is the custom background feature. It allows users to select a different background for the different chats. WhatsApp users on Windows Phone devices will most probably have 41 preinstalled images to choose among should they decide to personalize an individual chat. What's more, they can also take a new picture or browse their gallery for an image and apply it as a custom chat background.
Another pretty interesting feature – customizable notification tones – hit the private WhatsApp beta, too. It allows users to choose different alert tones for individual chats and group chats. There is no word if users will be able to apply a custom tone for different contacts.
However, there is no word whether or when these beta features and visual improvements will hit the official version of WhatsApp.
source: WPCentral (1), (2)