Windows 10 Technical Preview Build 9879 added practical changes to the taskbar, app windows, multi-monitor snapping, touchpad gestures, OneDrive syncing and media support. It was an Insider preview—not a consumer release—and Microsoft’s announcement mentioned “a few new icons” without identifying a new folder icon specifically.
When Build 9879 arrived—and who could install it
Microsoft announced Build 9879 for Windows Insiders in the Fast ring on November 12, 2014. It installed through Windows Update as a full in-place upgrade. Microsoft added the build to the Slow ring and made ISO images available through the Windows Insider Program on November 24. The announcement described it as the last new Insider build of 2014. Microsoft’s release announcement gives the original distribution details.
What changed in the interface?
Taskbar controls and app windows
Users could hide the Search and Task View buttons from the taskbar: right-click the taskbar and clear the relevant option. Microsoft also revised minimize and restore animations in response to Insider feedback.
Modern-app windows replaced the three-dot control with a three-line, hamburger-style icon intended to make charms and full-screen options easier to find. Microsoft noted that Insiders would see a few new icons, while stressing that the Windows 10 experience was still being developed. The release post does not say that a particular new folder icon was included.
Quick wins for a faster PC:
Scan for outdated or missing drivers - takes under a minuteDriver Scan →Clear out junk files and repair common Windows errorsFree Scan →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →#1 Best Overall
- Spacious Design: Measuring 21.1" wide and 14.1" deep, our lap desk comfortably fits most laptops up to 15.6". Extra room for accessories ensures convenience.
- Enhanced Functionality: Packed with handy features, including a 5x9" precision tracking mouse pad and a built-in phone slot for seamless work or video calls. Plus, enjoy ergonomic support with the integrated cushioned wrist rest.
- Cool Comfort: Enjoy a stable surface with our lap desk's dual bolster cushion, designed for comfort and airflow, keeping your lap cool during extended use.
- Durable Surface: Work with confidence on our lap desk's solid surface, featuring a sleek black carbon color, ensuring optimal air circulation to prevent your laptop from overheating.
- On-the-Go Convenience: With an integrated handle and lightweight design (2.8 lbs), our lap desk is portable for travel or moving around the house, offering flexibility in any space.
File Explorer and Insider feedback tools
Other refinements included File Explorer tweaks, the ability to pin favorite folders to Home, and modern-app dialogs that opened as properly windowed dialogs. Microsoft also added the Insider Hub app for news and quests. The Windows Feedback app gained sorting by trending topics, “Me Too” votes and recency, along with workflow and search improvements.
How did window management and touchpad input improve?
Snapping across monitors
Snap Assist was extended to snapping apps across multiple monitors, helping users arrange windows when working with more than one display.
Rank #2
- 5-in-1 Connectivity: Equipped with a 4K HDMI port, a 5 Gbps USB-C data port, two 5 Gbps USB-A ports, and a USB C 100W PD-IN port. Note: The USB C 100W PD-IN port supports only charging and does not support data transfer devices such as headphones or speakers.
- Powerful Pass-Through Charging: Supports up to 85W pass-through charging so you can power up your laptop while you use the hub. Note: Pass-through charging requires a charger (not included). Note: To achieve full power for iPad, we recommend using a 45W wall charger.
- Transfer Files in Seconds: Move files to and from your laptop at speeds of up to 5 Gbps via the USB-C and USB-A data ports. Note: The USB C 5Gbps Data port does not support video output.
- HD Display: Connect to the HDMI port to stream or mirror content to an external monitor in resolutions of up to 4K@30Hz. Note: The USB-C ports do not support video output.
- What You Get: Anker 332 USB-C Hub (5-in-1), welcome guide, our worry-free 18-month warranty, and friendly customer service.
New three-finger precision-touchpad gestures
On supported precision touchpads, Build 9879 added these gestures:
- Swipe up to open Task View.
- Swipe down to show the desktop.
- Flick left or right to switch back to the previous app.
- Move left or right to bring up Alt-Tab and select an app.
- Tap to open Search.
Why did OneDrive syncing change?
Windows 8.1’s online-only placeholders had confused users who saw files in File Explorer but found they were not available offline. Build 9879 introduced selective sync: users could sync all OneDrive files or choose which files and folders to keep on the PC. Microsoft presented File Explorer as the way to access OneDrive files in Windows 10 and said OneDrive behavior could be managed from its notification-area icon. Microsoft’s Build 9879 notes describe the change and its motivation.
Do these 3 things before closing this tab:
1Clear out junk files and repair common Windows errors2Fix the driver behind crashes, sound loss and screen glitches3Repair Windows errors before they cause bigger problemsRank #3
- Note: Not suitable for MacBooks released after 2023 or devices with a protruding front camera; Not applicable to full-screen or notch-style tempered glass screen protectors; Do not use on the rear camera of the phone.
- 💻 Why Do You Need a Webcam Cover Slide? — Safeguard your privacy by covering your webcam with our reliable webcam cover when not in use. Don't let anyone secretly watch you. Stay protected!
- ✅ Thin & Stylish — Enhance your laptop's functionality and aesthetics with our 0.027" ultra-thin webcam covers. Seamlessly close your laptop while adding a touch of sophistication.
- ✅ Fits Most Devices — Compatible with laptops, phones, tablets, desktops! Keep your privacy intact on Ap/ple, Mac/Book, iPh/one, iP/ad, H/P, L/novo, De/ll, Ac/er, As/us, Sa/msung devices.
- ✅ 365 Days Protection — Our upgraded 3.0 adhesive ensures a strong hold that won't damage your equipment. Experience reliable, long-term privacy protection day in and day out.
What was new for media playback and the browser?
MKV and H.265/HEVC support
Build 9860 had introduced native MKV support. Build 9879 made that experience more complete: MKV files could play in Windows Media Player and other desktop or modern apps, show thumbnails and metadata in File Explorer, and work in DLNA and Play To scenarios. The build also added Windows 10 platform support for H.265/HEVC.
An Edge rendering-engine experiment
The Internet Explorer team enabled the interoperability-focused Edge rendering engine for 10% of Windows Insiders in this build. That was a limited preview experiment, not a change enabled for every Build 9879 installation.
Rank #4
- Anti-Slip Surface - Transform your laptop into a mobile workstation with the AboveTEK portable laptop lap desk. The anti-slip surface provides a strong grip for laptops up to 15.6 inches(Diagonal), while the double rubber strip on the bottom ensures a stable display or typing experience on your lap, couch, or bed.
- Retractable Mouse Pad - Retractable laptop mouse pad extends on both directions for the left/right handed with elevation along the edges for stopping mouse from falling off. The size of laptop tray is 14" X 9.7" and the size of mouse pad is 7.4" X 6.1".
- Effective Heat Shield - The effective heat shield made of sturdy and thick material protects your laptop from overheating. Prioritizes your comfort and safety, an ideal lap pad or board for working anywhere.
- EASY to Carry and Store - With an ergonomic and simplistic design, the lap desk is portable to store in a backpack. Only 15" in size, 2.2 lb of weight and with slim 0.6 inch thickness, it is ready to be easily carried around.
- Widely Applicable - The smooth platform accommodates laptops and tablets up to 15.6 inches(Diagonal), making it a versatile accessory and one of the best gifts for mom, dad, students and professionals. Perfect for use as a laptop bed tray or tablet holder anywhere at home, library, or park.
What problems did Microsoft document?
Build 9879 was preview software, and Microsoft listed several known issues in its release notes:
- A black screen could appear during login or unlock. Microsoft expected a Windows Update fix. A later Microsoft Support notice traced a specific black or blank lock-screen failure to a WinLogon and LogonUI behavior change that could cause a deadlock; it said an update was available and required a restart.
- Some users could not connect to Distributed File System (DFS) network locations. Microsoft also expected a Windows Update fix for this issue.
- On some systems, duplicated driver installations could add 20GB or more to disk use, potentially leaving too little space to complete setup and causing a rollback. Microsoft presented this as a possible upper-threshold warning for affected systems, not an average or a population-wide statistic.
- Minimized Skype calls could disconnect, and Music playback could stop.
- Lync screen sharing had known problems.
Microsoft said the Skype, Music and Lync issues would not be fixed for Build 9879. A separate December 18, 2014 support notice said update KB3025380 included improvements that allowed Insiders on Build 9879 to continue receiving future Technical Preview builds.
Quick Recap
Best Value
- Spacious Design: Measuring 21.1" wide and 12" deep, our lap desk comfortably fits most laptops up to 15.6". Extra room for accessories ensures convenience.
- Enhanced Functionality: Packed with handy features, including a 5x9" precision tracking mouse pad and a built-in phone slot for seamless work or video calls. Plus, enjoy laptop support with the integrated device ledge.
- Cool Comfort: Enjoy a stable surface with our lap desk's dual bolster cushion, designed for comfort and airflow, keeping your lap cool during extended use.
- Durable Surface: Work with confidence on our lap desk's solid surface, featuring a blush pink color, ensuring optimal air circulation to prevent your laptop from overheating.
- On-the-Go Convenience: With an integrated handle and lightweight design (2.14 lbs), our lap desk is portable for travel or moving around the house, offering flexibility in any space.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
