A newer build of Windows 8.1 Update 1 has supposedly made it's way to notorious Russian leaker WZor

From Neowin:

As you can see, this may also be the first leak to appear online for the update.  WZor had previously predicted that a leak would happen on or by 15 January. 

The spring update will likely not bring a significant overhaul to the platform by any means and we will have to wait until April of 2015 to see any major changes to the platform when Windows 9 arrives. 

There's not much else to go on other than the screenshot that made it's way online over a week ago, but with an expected official release around the time of the BUILD conference, we don’t have to wait too long to see what the update includes.