Windows 10 build 10240 (th1)

Windows 10 build 10240 (th1) is the official RTM build of the original release of Windows 10 originally released to Windows Insiders in the Fast and Slow rings on 15 July 2015 and later generally released to the public on 29 July 2015. It is the first build to become available for consumers to install and was also available as a free upgrade for Windows 7, 8, and 8.1 users until 29 July 2016.

It contains very few changes over build 10176 (th1). However, it does include several changes over build 10166, the last preview build in the Threshold Wave 1 release cycle. These changes include the removal of the watermark and timebomb, widespread stability improvements and a branch change from  to.

Aside from these changes, build 10240 is a build which contains only limited changes over the previous builds.

Files from the ARM32 compile of this build were discovered on the Microsoft Symbol Server on 20 September 2022.

Build number
Build 10240.16384 is the last RTM build with the build number divisible by 16 and the delta number bumped to 16384. This is a remnant of the older 20-bit revision numbering scheme, which used the most significant bits in the delta number to encode extra information. The 4 least significant bits of the build number were reserved for the Service Pack number, although Microsoft hasn't produced a Service Pack since the release of Windows 8.

The limited range of usable revision numbers for a single Service Pack under this numbering scheme led to the build number of Windows Vista and Windows Server 2008 Service Pack 2 being bumped to 6003 towards the end of its lifetime in order to ensure that future updates continue to have distinct version numbers.

Dark theme
The dark theme can be enabled by applying the following entries to the registry hives. It will work with all Windows 10 editions except for Home edition.

Colored title bars
Microsoft did not introduce the option to change the color of title bars until Windows 10 build 10525. However, the colored title bars can be enabled in RTM by using a 3rd-party theme hack. Notice that inactive and active title bars have the same color, the only difference is that the inactive title bar text and buttons are grayed out.

Leftovers
Due to older code from beta builds or earlier versions of Windows not being removed, several older features can be re-enabled through registry tweaks or system file patches.

Windows 8.1 Start Screen
In July 2015, MetroFetro (notable for previously creating MetroUnlocker for builds of Windows 8) released modified versions of  and   (alongside a registry modification), which were created to restore the start screen from Windows 8.1 to the 2015 release build of Windows 10. However, these files were only released for the x86 architecture; x64 versions were released in May 2019, however these are known for being less reliable. It remains unknown as to how MetroFetro was able to restore tile-pinning functionality for his demo video.

97xx/DirectUI Start menu
On 12 November 2022, work was done to restore the legacy DirectUI-based start menu to the 2015 release build of Windows 10, based on the knowledge of Windows Server 2016 development builds still using it at this stage (such as in builds 10163 and 10244). This involves patching  in order to permanently trigger server SKU checks, resulting in the system using the older start menu over the standard XAML-based version.

Applications and shortcuts can be successfully pinned to the start menu, both to the list on the left-hand side and onto the right-hand side as tiles (unlike with the 8.1 start screen where this functionality is broken), but must be dragged into place from the All Apps menu since various context menu associations from earlier builds of Windows 10 are no longer functional.

This will also replace most flyouts (battery, network, volume, and date & time) with their legacy counterparts. However, Action Center will be broken and will not function unless the user manually rolls back to the Notifications flyout (from early builds of Windows 10) using the below registry modification.

98xx Notification flyout
The use of a registry file below removes the Action Center and brings back the Notifications flyout from early builds of Windows 10. It is partially broken as it wasn't intended to be used in RTM, as some of the icons are missing, and the text can turn into boxes like the "Clear all" text and turn text into pseudo-like in non-English versions of the operating system.

Other older flyouts
Several other older flyouts from Windows 8.x still exist in 10, most of which can be enabled by using various tweaks shown in an article posted on AskVG. Though it is commonly believed tweaks 1-8 in the listed article will work, tweak 9 will also work. Tweak 9 changes the action center back to the pre-release one. It can be restored by applying the following entry to the registry hives, then signing out of Windows and signing back in:

Windows 8.1 Taskbar jumplists
The use of the  patch, which restores a number of aforementioned pieces of legacy functionality intended for Server SKUs, will also restore taskbar jumplists to their previous Win32 state. The same behavior can be exhibited in Threshold 1-era builds of Windows Server 2016.

Notification Area Icons applet
The settings related to notification area icons are moved to the Settings app by this point, and the Notification Area Icons applet in Control Panel that was present in earlier versions of Windows is hidden. To open it, use the following command:

Personalization options in Control Panel
The desktop background and accent color settings is present in Settings → Personalization but the Control Panel applets are still present and can be opened using these commands:
 * Desktop Background:
 * Color and Appearance: any of these commands:

Windows 8 Search Charm
The Windows 8 Search Charm is still available in this build. It can be launched by running the following command:

Bugs

 * When choosing "Restore default icon behaviors" in the Notification Area Icons applet in Control Panel, the window hangs and then crashes. This bug does not always happen.