Seelen UI: A Web-First Desktop Reimagining Windows 11

Seelen UI arrives like a skin you can live inside — not just a theme or taskbar tweak, but a full, web‑powered desktop environment that can make Windows 11 feel like an entirely different operating system.

Background / Overview​

Seelen UI is a community‑driven project that replaces large parts of the Windows desktop experience with a web‑first shell built on Microsoft’s WebView (Edge WebView2). Rather than simply re-skinning Explorer or the taskbar, Seelen provides a top menu bar, a floating dock, custom flyouts for system controls, a tiling window manager, and an extensible resource ecosystem for themes and widgets — all assembled as a single, cohesive shell layer running on top of Windows. This architecture enables quick iteration, CSS‑driven theming, and a plugin model familiar to Linux desktop environment users. (github.com)
That combination is why Seelen often reads less like an app and more like a different OS experience sitting on the same kernel and drivers you already use. The project is active and versioned — the release channel shows regular updates and feature work such as workspace persistence, per‑monitor workspaces, wallpaper animations, and improved tiling behavior — which reflects serious engineering behind what might otherwise look like a novelty. (github.com)

---

Why Seelen UI feels like a whole new operating system​

Seelen’s ability to reframe the entire desktop workflow rests on four concrete pillars: a comprehensive UI replacement that strips away the familiar taskbar paradigm; deep theming and resource extensibility; a native‑style tiling window manager; and an integrated workspace model. Each pillar is worth unpacking because together they produce the “new OS” sensation.

1) The whole desktop UI changes — dock, top bar and custom flyouts​

Seelen doesn’t limit itself to shifting a few icons; it replaces the primary interaction surfaces.

• The traditional Windows taskbar is hidden and replaced by a dock that behaves and looks more like macOS’ dock: app icons, a Start button, and quick media controls appear as a single bottom hub.
• A menu/status bar lives at the top of the screen and hosts the clock, system toggles (network, Bluetooth), and user menus. Those toggles don’t simply open the native Windows flyouts — they bring up Seelen’s own HTML/CSS flyouts so the whole system feels consistent.
• Notifications, media now‑playing widgets, and quick access to recent files are all restyled and routed through Seelen’s UI layer rather than Windows’ native shells, increasing the sense that you’re operating inside a different environment.

That rework is what makes the visual and interaction shift so dramatic: muscle memory built around the bottom taskbar, Windows flyouts, and explorer‑driven menus is replaced with a new set of touchpoints that behave consistently with Seelen’s design system. Coverage of the project highlighted the dock and custom flyouts as core to the “different OS” feeling. (xda-developers.com)

2) Deep customization through resources and themes​

Where Windows 11 offers limited personalization, Seelen exposes a small but powerful extension ecosystem — called resources — that lets users modify not only colors and transparencies but the behavior of UI modules themselves.

• Resources include theme packages, widgets (weather, system monitors, media cards), sound packs, and icon sets.
• Community resources can add or remove toolbar modules, change dock animations to mimic macOS “bounce” or liquid glass effects, or install a “Fully customizable dock” resource that exposes granular controls over every dock element.
• Because the shell is web‑first, themes are implemented in a CSS layer, making it straightforward for designers to ship dramatic visual overhauls without low‑level patching or binary plugins. Release notes explicitly call out theme wrapping as a refactor that simplifies overriding styles. (seelen.io)

The result: radically different visual identities are achievable with modest community effort — and the same Seelen runtime can host wildly different experiences. That degree of visual and functional malleability is closer to what Linux desktop environments offer than anything Microsoft supplies.

3) A tiling window manager built into Windows​

Tiling window managers are a productivity staple on Linux but rare on Windows. Seelen implements an optional, full‑featured tiling window manager (TWM) that changes how windows are placed and managed:

• When enabled, newly opened windows are automatically tiled according to a chosen layout, ensuring no overlapping windows and easy side‑by‑side multi‑app workflows.
• The TWM supports keyboard control for moving focus, swapping containers, resizing tiles, and reordering windows — the sort of keyboard‑first control that serious multitaskers prize. Newer releases added keyboard container swapping and focus hotkeys. (github.com)
• The implementation supports floating windows as an escape hatch and includes predefined layouts that adjust automatically as windows open and close, maximizing available screen real estate.

If you’re used to snapping via Windows’ native FancyZones or manual tiling, Seelen’s TWM feels more automatic and persistent: it can keep windows organized by intent across sessions and monitors, which changes the way you think about app placement and multi‑project workflows. The project’s refactors and updates show iterative improvement in the tiling logic and multi‑monitor behavior. (seelen.io)

4) Workspaces that stay visible and per‑monitor persistence​

Virtual desktops exist in Windows 11, but Seelen integrates workspaces into the top menu bar in a way that mirrors GNOME or Ubuntu: visible workspace indicators, quick mouse switching, and keyboard shortcuts for moving windows between spaces.

• Workspaces can be configured to appear on specific monitors and persist across restarts, making the multi‑monitor, multi‑project setups more reliable. This per‑monitor persistence was explicitly added to recent releases. (github.com)
• The combination of workspaces and the tiling manager lets you build project‑oriented views where every app is visible and organized optimally for the task at hand.

This arrangement changes the mental model from “one desktop with overlapping windows” to “multiple focused views where each workspace is a curated arrangement.” For power users juggling documents, terminal windows, code editors, and chat clients, that shift is transformational.

---

How Seelen is built — benefits and tradeoffs​

Seelen’s web‑first strategy brings rapid extensibility and a low barrier for theming, but it also introduces tradeoffs you must understand.

WebView2 as the runtime: flexibility versus native performance​

Seelen runs inside Microsoft’s WebView2 runtime (Edge), which is both a strength and a constraint:

• Benefit: Developers can use HTML, CSS, and JavaScript to craft UI, which dramatically lowers the effort to ship themes, widgets, and plugin‑style resources. The project explicitly moved to a CSS layer for themes to make overrides easier. (seelen.io)
• Constraint: Some interactions that would be instantaneous in a native shell exhibit perceptible latency — e.g., hover previews, forced tiling, and inter‑process coordination — because WebView rendering and the glue code must mediate between the web UI and the native windowing APIs. Project notes and community reporting call out this performance headroom.

Seelen therefore trades a small amount of snappiness for massive gains in flexibility. For many users that’s an acceptable trade‑off; for users who prioritize ultra‑low latency or rely on GPU‑heavy workflows, the overhead may be noticeable.

System integration, maintenance surface and dependency management​

Because Seelen implements its own Wi‑Fi/Bluetooth panes, media flyouts, and notification styles rather than invoking native Windows dialogs, it must maintain those features across OS updates and diverse hardware. That increases the maintenance surface and can lead to subtle differences compared with the native shell.

• Seelen must detect and mirror system state (available networks, audio devices, notifications) and then present it through its web UI — a complex integration problem that the project gradually addresses through bug fixes and careful service work. Recent releases show fixes for media device selection and network listings. (github.com)
• The hard dependency on Edge/WebView2 means a system without the runtime will fail to run Seelen, and Seelen’s installer and checks attempt to warn users when WebView2 is missing. Release notes and changelogs include fixes for failure cases when the WebView2 runtime is absent. (seelen.io)

Those realities underline a trade: Seelen can innovate quickly but must shoulder the long tail of compatibility maintenance — a burden that single‑vendor shells like Explorer offload to Microsoft.

---

Releases, distribution and practical installation notes​

Seelen is actively released and versioned across GitHub and the project site, with multiple channels (release, beta, nightly) for different risk tolerances.

• Official releases and a changelog are visible on the project’s GitHub Releases page; recent stable tags and feature notes document ongoing work such as wallpaper resources, workspace persistence, and TWM improvements. (github.com)
• The project also publishes builds on its own site and maintains installer artifacts with patch notes that call out breaking changes and migration guidance between betas. (seelen.io)
• Installers are available both as GitHub assets and through alternative channels; some coverage recommends using the Microsoft Store build where available because it allows a more automatic update flow. Community writers emphasized store installs as the friendliest route for non‑developers. (xda-developers.com)

Practical guidance distilled from the project notes and community reporting:

• Back up your workspace and create a restore point before installing experimental shells.
• Prefer the release channel for day‑to‑day stability; use beta/nightly only to test new features.
• Ensure Edge’s WebView2 runtime is present before first launch; installers often fail in silent ways if WebView2 is missing. (seelen.io)

---

Strengths: where Seelen truly shines​

• Radical reimagining of the desktop: Seelen changes core UX anchors — taskbar, menus, notifications — so the change is immediate and immersive. Community write‑ups highlighted this as the project’s defining strength. (xda-developers.com)
• Extensibility and theming: The CSS/theme model and a resource marketplace unlock dramatic visual and functional changes without invasive system modifications.
• Tiling + workspaces: Built‑in tiling with keyboard control combined with visible workspace management helps power users and engineers reclaim screen real estate and mental focus.
• Active development and transparent changelogs: Frequent releases and public issue tracking mean the project is evolving — not abandoned — and many stability issues are actively triaged. (github.com)

---

Risks, limitations and things to watch​

No modern shell replacement is without downsides. The most important risks are technical, security‑related, and practical.

• Performance and latency: WebView‑mediated UI elements sometimes show delays compared with native shell interactions; tiling operations and previews may not be as instant as native equivalents. Project notes and community reports specifically call out this tradeoff.
• Compatibility edge cases: Not all native Windows apps or corner cases behave nicely under Seelen’s management. Some apps may ignore the tiling manager, fail to register for dock badges, or behave differently when forced into tiled layouts. Recent bug fixes target JetBrains apps and media widgets, which underscores the breadth of compatibility work required. (github.com)
• Surface area for bugs and regressions: By re‑implementing system panes (network, audio, notifications), Seelen increases the chance that a Windows update could temporarily break functionality until a patch is released. Users should be ready for intermittent regressions, especially on betas and new Windows builds. (github.com)
• Security model and trust: Any replacement shell must be trusted to handle input, display notifications, and coordinate app launches. Installing third‑party shells or heavy modifications requires trust in the developer and the release artifacts. Use verified channels and check signed installers when possible.
• Vendor/governance constraints: Microsoft has, over time, tightened certain shell internals and restricted replacement hooks in Windows. While Seelen currently operates as an overlay and uses WebView to sidestep low‑level integration, changes in OS policies could make certain approaches more brittle. This is a policy risk rather than a certainty and should be treated as such. Flagged as a cautionary consideration rather than a proven imminent problem.

---

Real‑world advice: how to experiment safely​

For enthusiasts and testers who want to try Seelen while minimizing disruption:

• Create a system restore point or full image backup before installing. Experimentation with shells touches startup and windowing behavior; restore points are cheap insurance.
• Start on a non‑critical machine or in a virtual machine (VM) to validate behavior with your apps and monitors.
• Use the release channel for day‑to‑day stability; use beta/nightly only when you want the latest features or to file reproducible bug reports.
• Verify you have the WebView2 runtime installed and up to date — Seelen will not run reliably without it. The project’s release notes contain explicit warnings and fixes for missing WebView2 cases. (seelen.io)
• Keep a fallback method to regain the native shell (hotkey or Task Manager kill) in case the UI becomes unresponsive.

---

What Seelen’s trajectory means for Windows customization​

Seelen demonstrates a clear appetite in the Windows community for desktop environments analogous to Linux: modular, themeable, and driven by extension ecosystems. Its existence and momentum signal three broader trends:

• Independent projects can achieve deep UX shifts without changing OS internals by layering web tech atop native hooks.
• There’s a persistent market for experiences that depart from Microsoft’s design decisions, particularly among power users and productivity seekers.
• Web technologies lower the barrier for contributors, which in turn accelerates visual innovation and creates small‑scale ecosystems of themes and resources.

Whether those trends change Microsoft’s product priorities is uncertain, but Seelen acts as a vivid proof of concept: you can build a DE‑like experience on Windows today and iterate quickly. The project’s public releases and changelogs document practical feature work such as per‑monitor workspaces, wallpaper resources, and tiling improvements — all indicators that the project is maturing beyond hobby status. (github.com)

---

Final analysis and verdict​

Seelen UI is not for everyone. It’s not a drop‑in replacement for enterprise desktops that demand strict compatibility and minimal maintenance overhead. But as a design experiment and a productivity platform for power users, Seelen is one of the most convincing attempts yet to bring the concept of desktop environments to Windows.
Strengths are clear and meaningful: radical visual change, deep theming and widget models, an integrated tiling manager, and persistent per‑monitor workspaces. Those strengths are balanced by real technical tradeoffs: reliance on WebView2, a larger maintenance surface, potential performance quirks, and compatibility edge cases — all of which the project acknowledges and iteratively addresses in its releases. (github.com)
For anyone curious about what a different Windows could feel like, Seelen delivers that sensation in a substantive way. For production environments, treat it as an experiment to be evaluated against workflow needs and risk appetite. In either case, the project deserves attention: it shows independent developers can reimagine desktop interaction models on Windows without kernel‑level hooks, and that kind of creative work pushes the platform forward — sometimes faster than official channels.

---

Seelen UI’s combination of a cohesive UI replacement, a resourceable theme/plugin model, a keyboard‑controllable tiling manager, and workspace persistence is why it can truly make Windows feel like a whole new operating system — just be mindful of the tradeoffs that come with running a web‑first shell on top of a closed OS. (github.com)

---

Source: xda-developers.com 4 reasons Seelen UI makes Windows feel like a whole new operating system