Draft:Feature lockout in Windows

On multiple occasions, Microsoft has used various mechanisms to hide early prototypes of new features in pre-release builds of Microsoft Windows before their formal introduction.

Windows 7
The development of Windows 7 marks the first time a deliberate centralized effort was introduced to conceal new features. Two separate mechanisms were introduced around build 6608:
 * Redpill, a series of registry checks usually present within the executable that implements a hidden feature. Used to enable Superbar, desktop slideshow, Start menu pinning, jump lists, Internet Explorer 8 enhancements, Aero Peek and Aero Shake.
 * Bluepill, which is implemented in the Application Compatibility Engine. It still results in a registry check, albeit indirect. Used to enable the new versions of Calculator, Paint, Sticky Notes and WordPad.

Build 7022 is the last known build to include both Redpill and Bluepill.

Windows 8
A more elaborate feature lockout system, called Redpill or SuperPill, was introduced during the development of Windows 8, which now takes advantage of the licensing subsystem as well as components that are not included with the base system. Noteworthy features hidden behind Redpill include the Start Screen, redesigned logon UI, new OOBE, Ribbon in Explorer, new Aero resources, and the pattern login (which later became the picture password login). However, while the majority of hidden features were locked using Redpill, simple registry checks remained the method of choice in some areas.

Product policies, a set of values usually used to determine what a particular edition can or cannot do, are now also used to control shell features. This made it considerably harder to overcome the protection, as the the majority of licensing data is signed and handled largely at kernel level. The intended method of delivering the Redpill policies into an existing install (clean installs do not ship with them) was activating against the internal  with the parameter. Unlocking the functionality manually implies the need to sacrifice parts of licensing functionality. Besides product policy sourced values, a sizable chunk of behavior hidden by Redpill also depends on an external library called, which is not included with the base Windows install and is only copied upon the activation of Redpill. This library is home to a large set of image and DirectUI markup assets, as well as a handful of functions used to initialize various parts of Metro such as Charms bar, Start screen search and the PC settings application.

Nearly all builds from Milestone 1 to shortly after the Developer Preview (currently 7779 to 8118) have Redpill implemented. Exceptions are builds from the  and   branches, e.g. build 8064, which do not have any form of Redpill implemented as all of the Metro components were removed at compile time. These builds were released to Microsoft partners via the Ecosystem Engineering Access Program (EEAP). The only available build with Redpill unlocked out of the box is build 8102, the Developer Preview. Due to the complexity of the mechanism, a formerly widespread method of unlocking Redpill on other builds was to use modified components from build 8102, although the reliability of this method decreased with earlier builds. It wasn't until the introduction of Redlock with a custom version of  reimplemented from scratch that Redpill could be unlocked for builds before build 7927.