GitHub - alokdhir/spinwin: macOS menubar app that visually rotates or spins another app's window, using ScreenCaptureKit to fake what macOS has no API to do

A macOS menubar utility that visually rotates a selected window by any angle (90° increments, arbitrary angles, or a continuous spin).

How it works (and why) macOS has no public API to rotate another app's window. Real rotation would require private SkyLight calls (CGSSetWindowTransform) with System Integrity Protection disabled — not worth it. Instead, SpinWin fakes it:

Hide the selected window off-screen via the Accessibility API. It keeps rendering there, so it can still be captured. Capture its contents continuously with ScreenCaptureKit (SCStream + desktopIndependentWindow filter) — this grabs only that window's buffer, so the overlay never mirrors itself. Draw the frames in a transparent, borderless overlay window placed where the original was, rotated with a CALayer transform.

Because it's a layer transform, any angle works — the overlay is sized to the rotated content's bounding box so nothing clips, and a diagonal-sized square is used while spinning. Usage The easiest way to get SpinWin is the latest release — the download is signed with a Developer ID and notarized by Apple, so it launches without Gatekeeper warnings. Or build it yourself: ./scripts/build-app.sh # builds SpinWin.app (release) open SpinWin.app # grant Screen Recording + Accessibility For quick iteration during development: swift build && swift run SpinWin Left-click the menubar icon to start: choose a rotation in the bottom options bar (a preset angle, a spin speed + direction, or free rotation), then click the window you want. Drag the overlay to reposition it; drag its handle to rotate freely. Press Esc on the overlay to stop and restore the window. Right-click (or Control-click) the icon for the menu: active rotations (with per-window angle/spin controls), Stop all, and Quit. Permissions

Screen Recording — to capture the window contents. Accessibility — to move the source window off-screen and restore it.

Current limitations

The overlay is a live picture, not interactive. You can drag and rotate it, but clicks and keystrokes are not sent to the real window underneath. Mission Control / Exposé leak. The hidden window is parked off-screen but still a real window, so Exposé shows it unrotated.

There is no public API to exclude another app's window from Mission Control, and minimizing it would stop the capture. Some apps throttle rendering of off-screen windows, which can slow the feed. A window that resizes itself while rotated keeps its original footprint. You can't drag-resize the hidden window, but an app can still resize it on its own (a video player adapting to a new track, a terminal responding to an escape sequence). The capture is letterboxed into the original size until you stop and rotate it again.

Layout

File Role

main.swift App entry point (accessory/menubar policy)

AppDelegate.swift Menubar item; left-click rotates, right-click opens menu

Permissions.swift Requests Screen Recording + Accessibility at launch

WindowPicker.swift Full-screen window picker + rotation options bar

RotationManager.swift Tracks one rotation session per window

RotationSession.swift Orchestrates hide → capture → overlay per window

CaptureEngine.swift ScreenCaptureKit stream → IOSurface frames

OverlayWindow.swift Transparent rotating/spinning overlay, drag

AccessibilityWindowMover.swift Move source window off-screen + restore

ActivationChoice.swift Initial rotation choice (angle/spin/free)

SpinDirection.swift Clockwise/counterclockwise spin option

MenuBarIcon.swift Draws the menubar icon