SnapLayouts 10

Unofficial Snap Layouts for Windows 10. Hover over a window's Maximize button for about 300 ms and a Windows 11-style menu appears with six layouts. Click a zone to snap the window there — no keyboard shortcuts and no FancyZones.

Unofficial project. Not affiliated with, sponsored by, or approved by Microsoft. Windows, Snap Layouts, and Snap Assist are trademarks of Microsoft Corporation. See NOTICE.md.

• Version: 1.4.0
• Platform: Windows 10 22H2 x64, .NET Framework 4.8
• Tested on: Windows 10 IoT Enterprise 22H2, build 19045.6456, 1920 × 1080, 100% DPI
• UI language: English
• Portable: no installer, no network access, no telemetry

Download

Latest release: GitHub Releases

• SnapLayouts10.exe — portable app
• SnapLayouts10-1.4.0-portable.zip — app + documentation
• SnapLayouts10-1.4.0-source.zip — full source
• SHA256SUMS.txt — integrity

Documentation

Document	Contents
TESTING.md	environment, test steps, results, limitations
COMPATIBILITY.md	tested applications and known limitations
WINDOWS11-DESIGN.md	visual analysis of Windows 11 and design decisions
PUBLISHING-GITHUB.md	release and publication guide
CHANGELOG.md	version history
CONTRIBUTING.md	build, style, testing, pull requests
SECURITY.md	vulnerability reporting and privacy

Features

1. Detects the Maximize button with WM_NCHITTEST (HTMAXBUTTON), without global mouse hooks.
2. Shows the layout menu after 300 ms of pointer rest (configurable).
3. Six layouts with 2, 3, or 4 zones, styled after Windows 11.
4. Highlights the zone under the cursor and snaps on click.
5. Works with the monitor under the cursor, per-monitor DPI, and physical coordinates.
6. Compensates for invisible DWM window borders so snapped windows align visually.
7. Opens a visual Snap Assist in the remaining zone with live window previews.
8. Runs in the system tray with settings and optional automatic startup.

Layouts

#	Layout	Zones
1	2 equal columns	2
2	2 columns 70/30	2
3	3 equal columns	3
4	Left + 2 right	3
5	4 quadrants	4
6	Large left + 3 right	4

Layouts can be enabled or disabled individually in Settings.

Install and run

1. Copy SnapLayouts10.exe to a permanent folder, for example C:\Users\<user>\AppData\Local\Programs\SnapLayouts10\.
2. Run SnapLayouts10.exe. The app appears in the system tray.
3. Right-click the tray icon:
   • Snap Layouts: enabled — toggle detection;
   • Start with Windows: yes/no — manage the HKCU\...\Run entry;
   • Settings... — delay, gap, Snap Assist, active layouts;
   • About, Open data folder, Exit.
4. Double-click the tray icon to open Settings.

Run with --settings to open Settings immediately. Run with --debug to enable detailed logging.

Usage

1. Focus the window you want to snap (Notepad, Explorer, Chrome, etc.).
2. Rest the pointer on the Maximize button for about 300 ms.
3. Choose a zone in the flyout.
4. The window moves to that zone. If Snap Assist is enabled, choose another window for the next zone, or press Esc.

The flyout closes when the pointer leaves it, when the target loses focus, or when the Maximize button is pressed. Hovering the Restore Down button of a maximized window works too; the window is restored before snapping.

Settings

Settings file: %APPDATA%\SnapLayouts10\settings.ini

enabled=1
hoverdelayms=300
gap=8
snapassist=1
startwithwindows=0
firstrun=0
layouts=1,1,1,1,1,1

• hoverdelayms — 200…700 ms in the UI (1000 ms maximum in the file).
• gap — gap between windows, 0…16 px in the UI.
• layouts — one 1/0 for each of the six layouts.

Log: %APPDATA%\SnapLayouts10\snap.log (automatic rotation at 256 KB).

How it works

Maximize button detection

A 40 ms timer:

1. reads the pointer position (GetCursorPos);
2. finds the window under the pointer (WindowFromPoint + GetAncestor(GA_ROOT));
3. verifies that it is the foreground window, visible, and has WS_MAXIMIZEBOX;
4. sends WM_NCHITTEST and checks for HTMAXBUTTON (9).

If the window does not respond within 80 ms, a fallback region in the top-right corner is used. No global mouse hook is installed, so the input thread is not blocked.

Flyout

After 300 ms, the app computes the monitor work area (MonitorFromPoint + GetMonitorInfo) and the target DPI (GetDpiForWindow). The flyout is a borderless, rounded, topmost window with WS_EX_NOACTIVATE, so it does not steal focus. It opens below the Maximize button and flips above when there is not enough room.

Layout previews are drawn directly on the panel, without card backgrounds, with large rounded zones and a settings gear. The background uses a blurred screen capture with an acrylic-style tint.

Snapping

For each zone, the app computes a physical-pixel rectangle, restores maximized/minimized windows, and calls SetWindowPos. The difference between GetWindowRect and DWMWA_EXTENDED_FRAME_BOUNDS is compensated so invisible borders do not produce uneven gaps.

Visual Snap Assist

After the first snap, the selector opens inside the remaining zone. Each candidate window is shown as a separate floating preview with a shadow, over a blurred wallpaper background. Previews are rendered live with DWM (DwmRegisterThumbnail + DwmUpdateThumbnailProperties) and preserve window aspect ratios. Click a preview to snap it; Esc or a click outside cancels. Up to six windows are shown.

Multiple monitors

The work area, DPI, and flyout placement are computed for the monitor under the cursor. Snapping uses the target monitor's work area. APIs such as GetDpiForWindow and MonitorFromPoint are per-monitor aware, and the manifest declares PerMonitorV2.

Build from source

Only components included in Windows 10 are required:

• C:\Windows\Microsoft.NET\Framework64\v4.0.30319\csc.exe
• .NET Framework 4.8 (included in Windows 10 22H2)
• Windows PowerShell 5.1

powershell.exe -NoProfile -ExecutionPolicy Bypass -File .\build.ps1

Output: dist\SnapLayouts10.exe. The script also generates assets\app.ico if missing. Nothing is downloaded from the network.

Automated geometry tests:

powershell.exe -NoProfile -ExecutionPolicy Bypass -File .\tools\test-geometry.ps1

Release packages:

powershell.exe -NoProfile -ExecutionPolicy Bypass -File .\package.ps1

CI (.github/workflows/build.yml) builds, tests, and packages on windows-latest. .github/workflows/release.yml publishes a release when a v* tag is pushed. See PUBLISHING-GITHUB.md.

Project structure

SnapLayouts10/
├── .github/
│   ├── workflows/             # build CI + automatic release
│   ├── ISSUE_TEMPLATE/
│   └── PULL_REQUEST_TEMPLATE.md
├── build.ps1                  # csc build
├── package.ps1                # portable/source packages + SHA-256
├── README.md
├── LICENSE
├── NOTICE.md
├── CHANGELOG.md
├── CONTRIBUTING.md
├── SECURITY.md
├── assets/app.ico
├── dist/                      # generated locally, ignored by Git
├── docs/
│   ├── TESTING.md
│   ├── COMPATIBILITY.md
│   ├── WINDOWS11-DESIGN.md
│   ├── PUBLISHING-GITHUB.md
│   ├── preview-flyout.png
│   └── social-preview.png
├── src/                       # application source
└── tools/                     # icon generator + geometry tests

Testing

See TESTING.md. On the test machine:

• Maximize detection worked for Notepad and Chrome (WM_NCHITTEST = 9);
• the flyout appeared after roughly 360–430 ms from the first detection tick;
• snapping worked for 2 columns, 70/30, 3 columns, and 4 quadrants;
• Snap Assist opened in the free zone with six floating live previews and snapped the selected window;
• settings, startup, and tray behavior were verified;
• automated geometry tests pass for all six layouts and a simulated second monitor.

Known limitations

• Windows with fully custom title bars that do not return HTMAXBUTTON may not be detected.
• Elevated applications may reject SetWindowPos from a normal-integrity process (UIPI). Run SnapLayouts 10 as administrator if you need that.
• Multi-monitor support is implemented with per-monitor APIs, but hardware testing used one physical monitor.
• Snap Assist shows up to six windows, selected by Z-order.
• Preview rendering depends on DWM; if a thumbnail cannot be created, the app icon is shown.
• The executable is not code-signed. SmartScreen may warn on first run. Verify the hash or build from source.
• Windows 7/8 are not supported; target is Windows 10 22H2 x64 (also runs on Windows 11).

Privacy

The app has no network, telemetry, or auto-update. It writes only:

• %APPDATA%\SnapLayouts10\settings.ini
• %APPDATA%\SnapLayouts10\snap.log
• optionally, at your request, HKCU\Software\Microsoft\Windows\CurrentVersion\Run\SnapLayouts10

The log may contain window titles when --debug is enabled. Remove sensitive data before sharing it. See SECURITY.md.

Contributing

Contributions are welcome. Read CONTRIBUTING.md and CODE_OF_CONDUCT.md. For vulnerabilities, use SECURITY.md, not a public issue.

License

MIT © 2026 SnapLayouts 10 contributors.

Unofficial project; see NOTICE.md.