Since the release of the Technical Preview build of Windows 10 and the end of January 2015, Microsoft has been continuously experimenting and developing newer builds with the aim of refining this operating system for an official launch by the end of 2015. According to some sources, images of one of the latest builds, build 10031, have recently surfaced online. These images provide us with a more specific view of the features Microsoft is experimenting with. And these images were leaked from WZor - a Russian blogger specializing in obtaining leaked information from within the US software company.
The notable aspect here is that build 10031 features a somewhat translucent Start menu by Microsoft. Currently, the Windows 10 version for phones also features a translucent Start menu. However, Microsoft has opted for two different approaches for the two versions. On phones, the component made translucent is the tile; whereas on Windows 10 for PCs and tablets, only the background behind the Start menu is blurred.
Microsoft is actively working on integrating the Spartan web browser, successor to IE, into upcoming builds. However, according to sources, Spartan still requires a lot of time to be completed. Features such as favorites, history, and download manager are still not functional on Spartan. Microsoft has also not integrated tools for developers yet, and Spartan still lacks an extension system that many users are eagerly awaiting.
Source: Ars Technica