Windows 10 Mobile Redstone 3

Windows 10 Mobile Redstone 3
	Version of Microsoft Windows
OS family	Windows 10 (NT 10.0)
Codename	Redstone 3
Architecture	ARM32 (ARMv7)
Latest build	10.0.16241.1001
Replaces
	Windows 10 Mobile Creators Update

A version of Windows 10 Mobile based on the Redstone 3 codebase was initially planned to be released following the Creators Update. It would have included drastic overhauls to the Continuum feature set in an attempt to provide feature parity with desktop releases of Windows 10, such as overlapped windowing support, independent per-mode Start menu layouts, system tray and Action Center functionality in the taskbar, and further general improvements to the overall user experience.^[1]

Problems encountered during development led to the creation and release of a stopgap release based on a direct fork of the Creators Update.^[2] It was eventually cancelled due to a reallocation of resources towards the Windows Core OS project.

New features and changes[edit | edit source]

The update would have primarily focused on introducing significant improvements to the Continuum shell by bringing feature parity with Windows desktop releases such as overlapping windows, invoking the Start menu by pressing the Windows key on a user's keyboard, as well as independent Start menu layouts for both mobile and desktop interfaces. It would have also featured the ability to pin applications to the taskbar, the addition of the taskbar system tray and a reimplemented version of the Action Center, as well as enabling the ability to wirelessly connect to other non-Microsoft display docks and individual screen timeouts on both the phone and on a connected display.^[1] The enforcement of the navigation bar in the mobile user interface would have also necessitated dropping support for devices with physical navigation buttons, particularly those released during Windows Phone 8.1's lifespan. Support for Windows Phone 8 applications was also removed in whole, as they relied on a minimal version of the Silverlight application framework.

Internally, the update would have also introduced the Composable Shell (CShell), a framework that allowed developers to write user interfaces for any platform type and form factor by exploiting the capabilities of the Universal Windows Platform (UWP), in which individual UWP applications (known as Composers) act as fully-fledged system shells; these interfaces would have also shared user interface controls with each other. Its development required a complete rewrite of the existing Splash system shell, in turn causing serious stability, performance and functionality regressions.

Cancellation, shift of focus to Windows Core OS[edit | edit source]

The overall state of the Redstone 3 mobile codebase led to Microsoft making the decision to provide a stopgap release (commonly known as Feature 2 and based upon the older Creators Update codebase) to Windows Insiders as work to further integrate the Composable Shell into the OneCore codebase continued in internal branches, in an effort to provide engineers additional time to produce a workable release that would have shipped to a wider user base; this was clarified by Dona Sarkar as "converging code into OneCore" in the release announcement of build 15204:^[2]

As we release new builds from our Development Branch for PC, we will also be doing the same for Windows 10 Mobile just like we have been in the past. However, Windows Insiders will likely notice some minor differences. The biggest difference being that the build number and branch won’t match the builds we will be releasing for PC. This is a result of more work we’re doing to converge code into OneCore – the heart of Windows across PC, tablet, phone, IoT, HoloLens, Xbox and more as we continue to develop new improvements for Windows 10 Mobile and our enterprise customers.
— Dona Sarkar, Windows Insider Blog^[2]

Around the time build 16200 was compiled, work shifted focus towards the Windows Core OS project, a decision that proved turbulent as the Windows 10 Mobile project was effectively discontinued under the orders of then-Windows project lead Terry Myerson. Initial bringup work for most base Windows Core OS functionality was done against the Windows 10 Mobile codebase as a test bed.

All internal Windows development branches quickly stopped compiling code for Windows 10 Mobile as soon as the WCOS core entered into a mostly functional state (around the 1623x-series build range), with the last branch to ever compile code for MobileCore being rs_onecore_base2.