I have a multi-monitor setup and spend a lot of time typing in Codex and other AI agents. When I move to another monitor to run a shortcut, focus often stays in Codex or another text app, so the shortcut runs in the wrong place.I asked ChatGPT if there was a macOS setting or free app for this. It couldn t find one that did exactly what I wanted, so I asked it to prototype one. It built a working version in one go.I then used Codex to add sensible defaults, focus protection, an optional display border, packaging, documentation, an MPL 2.0 license, a logo, and screenshots.ScreenFocus is the result: keyboard focus follows the pointer across displays while global shortcuts keep working.This was my first native Mac app, and I used GPT-5.6 Sol with High reasoning. If you check out the README, help docs, and other Markdown files, you might be surprised by how complete it feels.I also added Launch at Login, full-border and corner-marker styles, custom colors, automatic pausing when only one monitor is connected, and a few other settings.