ScreenBox

A tiny macOS menu bar app for drawing highlight boxes on screen while recording or presenting.

Press a hotkey, drag a box around whatever you're talking about, and it fades away on its own. No editing pass, no timeline annotations.

Build

./build.sh
open build/ScreenBox.app

Requires the Swift toolchain (Xcode or Command Line Tools). No dependencies.

To keep it around: drag build/ScreenBox.app to /Applications and add it to System Settings → General → Login Items.

Use

⌃⌥⌘B toggles draw mode on whichever screen the mouse is on.

While drawing:

Key	Action
drag	draw with the current tool
P A R O T H	freehand / arrow / rectangle / ellipse / text / highlighter
1–5	blue / red / green / yellow / purple
S	toggle the spotlight
[ ]	thinner / thicker stroke (spotlight size, while it's up)
− =	less / more corner radius
F	toggle fade-out on/off
⌘Z	undo last mark
C	clear all, stay in draw mode
esc	clear and exit draw mode

The highlighter drags a wide translucent band in the current colour, so whatever it covers still reads through — yellow over a line of code or a paragraph works the way you'd expect. Its width follows the stroke thickness ([ and ]), scaled up.

The spotlight dims the whole screen except a soft-edged circle that follows the pointer, for pulling attention to one part of a demo. It's a mode, not a tool: every drawing tool still works while it's on. [ and ] resize it, or pick a size from Spotlight Size in the menu.

By default the pointer is left alone in draw mode — no crosshair, no I-beam — so a recording doesn't give away that an annotation tool is running. Turn off Keep Normal Cursor in the menu if you'd rather have the crosshair back.

⌘Z only applies to marks still on screen. With fade on (the default) a mark is gone about a third of a second after you release the mouse, so there is usually nothing left to undo. Press F to turn fade off first.

Preferences

Colour, thickness, corner radius, fade speed, and fade on/off all live in the menu bar and are saved automatically — change them however you like and they'll be the same next launch. Keyboard changes made mid-draw persist too.

Defaults: yellow, 4pt, square corners, fast fade.

Preferences are stored in UserDefaults under local.screenbox. To reset everything:

defaults delete local.screenbox

Adding a preference

Sources/Prefs.swift is the single source of truth. Add a Key case, a computed property, and a default in register(defaults:). Because every write fires onChange, the menu re-ticks and the live overlay redraws with no extra wiring.

Releases

The version is derived from git tags — nothing to bump by hand. build.sh stamps CFBundleShortVersionString from the latest tag (v1.2.0 → 1.2.0, or 1.2.0-dev for commits after it) and CFBundleVersion from the commit count. The running version shows at the bottom of the menu.

To cut a release:

./scripts/release.sh 1.2.0

It refuses unless you're on a clean main, fast-forwards, checks the tag is free, does a smoke build so a broken commit can't burn a tag, then tags and pushes.

The push triggers .github/workflows/release.yml, which builds a universal binary on macos-latest, packages it as both a drag-to-install .dmg and a .zip, and publishes a GitHub release with both attached.

To build a disk image by hand:

./build.sh
./scripts/make-dmg.sh          # -> build/ScreenBox-<version>.dmg

The app is only ad-hoc signed, so Gatekeeper quarantines it on download and the release notes tell people to right-click → Open (or run xattr -dr com.apple.quarantine). Fixing that properly needs an Apple Developer account: sign with a Developer ID certificate, then xcrun notarytool submit --wait and xcrun stapler staple in the workflow.

Notes

• The overlay window only exists while draw mode is active, so it never intercepts clicks when you're working normally.
• While draw mode is active the overlay swallows clicks on that screen — press esc before advancing slides.
• Boxes are stroked with a dark halo so they stay readable on light and dark backgrounds.
• Uses a Carbon hotkey, so no Accessibility permission is required.
• Draws over normal windows but not over fullscreen apps.

Licence

MIT — see LICENSE.

Fade speed presets

Preset	Hold	Fade
Instant	0s	0.15s
Fast (default)	0.15s	0.2s
Medium	0.35s	0.4s
Slow	1.0s	0.8s

Edit Prefs.speedChoices in Sources/Prefs.swift to change or add presets.