Microsoft is reviving one of the most requested Copilot interfaces in a new Windows 11 test build. The company is experimenting with a docked sidebar mode that lets users pin the AI assistant to the left or right edge of the desktop, according to a late May 2026 update to the Copilot app. This marks a significant shift from the free-floating window that replaced the original sidebar, addressing months of user feedback.

The change arrives as part of an ongoing series of Copilot UI experiments. Early Windows 11 Copilot iterations featured a fixed sidebar that hogged precious screen real estate but at least felt like a permanent desktop companion. Microsoft later decoupled Copilot into a standalone movable window, which offered flexibility but lost the integrated feel many users preferred. Now, the pendulum is swinging back, with a twist: you can choose your edge.

Dock left or right? That simple choice could alter daily workflows. Power users who live in multiple windows will appreciate being able to snap the assistant to the opposite side of their primary focus, avoiding overlap. It’s a small quality-of-life improvement with outsized impact, especially on ultra-wide monitors where a persistent sidebar can serve as a constant reference panel without cluttering the center workspace.

The rocky road of Copilot’s real estate

Copilot’s interface has been a moving target since its debut. The initial sidebar integration in Windows 11 felt like a natural extension of the taskbar, always within reach but permanently anchored to the right side. It couldn’t be moved, resized, or hidden, and it forced all other windows to resize awkwardly. The backlash was immediate: users complained about lost horizontal pixels, especially on smaller screens.

Microsoft responded by cutting Copilot loose as a standard desktop app in 2024. That decoupled version could be dragged anywhere, minimized to the taskbar like any other program, and even snapped to half-screen. It solved the screen real estate problem but created a new one: Copilot no longer felt like a system-level feature. It was just another window competing for attention. The assistant lost its omnipresence, and engagement metrics reportedly dipped.

Insider builds over the past two years have toyed with several hybrid ideas. A “companion mode” briefly appeared in Dev Channel flights, allowing Copilot to attach to a side of the screen without forcing other windows to resize. That implementation was buggy and short-lived. Another experiment let the sidebar auto-hide, sliding out only when triggered. None of these ever made it to stable builds. The late May 2026 test suggests Microsoft has finally landed on a compromise: a dockable sidebar that behaves as a permanent fixture but gives users control over its placement.

How the docked sidebar works

According to details from the test, enabling the new docked mode re-pins Copilot to the desktop edge as a slim, resizable panel. Unlike the original rigid sidebar, this version can switch between left and right docking via a new button in the app’s interface or through a settings toggle. When docked, it reclaims its always-on-top behavior, staying visible even as you work in other apps. Importantly, other windows no longer awkwardly resize to accommodate it; instead, the dock uses a translucent overlay or a smart z-ordering that lets it sit beside or above content without permanently shrinking the work area.

Windows that collide with the dock get a subtle boundary offset, much like how the taskbar behaves in auto-hide mode. Alternatively, users can set the dock to always be visible, treating it as a persistent frame. Early testers note that the dock maintains its state across desktop switches and monitor setups, a crucial improvement over the original sidebar’s finicky multi-monitor behavior.

The app itself remains decoupled in the sense that it’s still a window—just one with a special docking ability. That means you can undock it back to a floating window with a single click. This fluid transition between docked and undocked modes could satisfy both camps: those who want a constant AI companion and those who prefer to invoke it only when needed.

User feedback: what the forums are saying

Even in early testing, community reaction is sharply divided. On Windows enthusiast forums, long-time Copilot users are celebrating the return of a permanent sidebar. “Finally, they listened,” one user posted. “I’ve been using a third-party tool to mimic this behavior for months.” Many highlight that the docked mode reduces the cognitive load of constantly Alt-Tabbing or snapping a floating Copilot window next to their work.

Detractors, however, remain skeptical. Some argue that any edge-docked panel still wastes desktop real estate, no matter how clever the window management. Others worry that the feature is a gateway to more persistent, unclosable Microsoft services. One vocal critic in the WindowsInsider subreddit called it “bloatware creeping back onto my desktop.”

Early comparisons to Apple’s Sidebar in macOS Sequoia are inevitable. Apple’s implementation uses a similar edge-pinning concept but ties it to a specific workspace. Microsoft’s approach appears more flexible, allowing the sidebar to follow you across virtual desktops. Whether that flexibility leads to a cluttered or harmonious experience depends heavily on execution.

Technical under the hood

The docked sidebar isn’t just a cosmetic change; it requires deep integration with the Windows shell. Sources indicate that Microsoft is leveraging new APIs introduced in the Windows 11 24H2 kernel that allow app containers to register as “peripheral panels.” These panels can request a docked state that the desktop window manager (DWM) respects when arranging other windows. This API may eventually be available to third-party developers, potentially opening the door for a new class of persistent desktop gadgets—ironic, given Microsoft’s retirement of the original Windows Gadgets over security concerns.

Performance-wise, the new docking mode is surprisingly lightweight. The sidebar consumes minimal GPU resources when idle, thanks to a new compositing layer that treats it as a separate, low-priority surface. This contrasts with the old Copilot sidebar, which was infamous for hogging system resources when open for extended periods.

What this means for Windows 11’s AI future

The return of the docked sidebar signals that Microsoft is committed to making Copilot a first-class desktop citizen. It’s not just another app you might install; it’s meant to be used all day, every day. The ability to pin it to the edge ensures it’s always in your peripheral vision, ready to answer quick questions, summarize documents, or control system settings without breaking your flow.

This fits into a broader vision of ambient computing. Microsoft wants Copilot to be the glue between local apps, cloud services, and web content. A permanent sidebar could serve as a universal clipboard holder, a task switcher, or a live dashboard for notifications and calendar events. Integrations with Microsoft 365 and third-party plugins could turn it into a command center that rivals the Start menu itself.

Rivals are pushing similar concepts. Google’s Bard integration in ChromeOS places a floating panel near the bottom of the screen, while Samsung’s Galaxy AI uses an edge bar on phones. Microsoft’s advantage is the PC’s expansive screen real estate, where a sidebar feels more natural than on mobile.

A lesson in listening (slowly)

Microsoft’s iterative approach to Copilot’s UI mirrors its broader development philosophy for Windows 11: ship, collect data, pivot. The original sidebar shipped to mixed reviews. The decoupled window shipped to more mixed reviews. Now, the docked sidebar attempts to merge the best of both worlds. It’s a pattern the company has followed with the Start menu, taskbar, and browser—evolving through feedback and usage telemetry.

This time, the testing window seems shorter than usual. The late May 2026 build is already in the Dev Channel, and some insiders predict a Beta Channel flight within weeks. If all goes well, the docked sidebar could hit general availability as part of the upcoming Windows 11 26H2 feature update, tentatively scheduled for October 2026. That timeline would give teams just a few months to squash bugs and refine the API.

What you can do now

If you’re eager to test the new docking mode, you’ll need to be in the Windows Insider Program’s Dev Channel. Install the latest build and ensure the Copilot app is updated to version 2.6.2505 or later. Toggle the docking option in Copilot’s settings under “Personalization.” Bear in mind that this is early code; you may encounter visual glitches, especially with custom scaling and multi-monitor setups.

For those who prefer stability, it’s wise to wait for the Beta or Release Preview rings. Use the time to think about how a persistent AI sidebar could fit into your workflow. Set up virtual desktops accordingly, and consider which apps you’d want to coexist with Copilot.

The bottom line

The docked sidebar test is a clear sign that Microsoft isn’t done reinventing the desktop. By restoring a much-requested feature with added flexibility, the company is acknowledging that one size doesn’t fit all. The ability to pin Copilot left or right may seem like a minor tweak, but it represents a deeper commitment to making AI an integral, customizable part of the Windows experience.

As the test progresses, the key metrics will be stability and user satisfaction. If Microsoft can deliver a sidebar that’s useful without being intrusive, it could set a new standard for desktop AI interfaces. If not, it risks another round of feature churn that frustrates the most loyal Windows users. Either way, late May 2026 just got a little more interesting for Windows enthusiasts.