Show HN: X11 tool to share a screen area in any video meeting

Overall reaction & use cases

• Many commenters find the tool immediately useful, especially for ultra-wide or large monitors where sharing the whole screen is impractical.
• Common workflow: use a helper like slop or a fullscreen screenshot to get coordinates, then invoke the tool to mirror just that region into a virtual monitor for Meet/Zoom/etc.
• People like the small size and simplicity of the C++ implementation and how it showcases X11’s “hackability.”

Alternative tools and simple recipes

• Alternatives on X11:
  • Xephyr/Xnest with a separate nested display as a demo environment.
  • xrandr --setmonitor alone can create virtual monitors; combined with slop and simple shell pipelines, you can replicate most of the tool’s behavior.
  • xzoom can also zoom and share portions of the screen.
• OBS can crop part of a screen and present it as a source, but is seen as much heavier and more configuration-intensive than a tiny CLI tool.

Wayland vs X11 debate

• Several comments note this exact trick is not feasible under Wayland in the same direct way.
• Wayland’s model intentionally blocks arbitrary screen and input snooping; screen capture is routed through portals (e.g., KDE offers rectangular region and virtual output sharing).
• Some praise this as better security and sandboxing; others criticize it as “security theater” that breaks useful workflows, hurts accessibility, and fragments protocols.
• There is disagreement on how serious the real-world threat of X11-based spying is versus the cost in flexibility and tooling.

Code quality, performance, and correctness

• Some criticize the initial implementation for lacking error handling and using a sleep loop instead of proper signal/event handling.
• Others counter that in this use case CPU impact is negligible; later comments note the code was updated to use sigwait.
• There is brief discussion on how very short sleeps interact with CPU scheduling, power states, and battery life, with no full consensus.

Meeting platforms, UX, and unmet need

• Commenters are surprised that built-in region-sharing is still missing in many meeting tools; some note this limitation has even influenced choice of platform.
• A few highlight that features like multi-window sharing in Zoom are poorly discovered, often only found via documentation or chance.
• Some report that modern KDE/Wayland + browser combos already offer region and virtual output sharing via standard dialogs.

Other platforms

• macOS equivalents: commercial “Advanced Screen Share” and open-source DeskPad are mentioned, though not identical in behavior.
• Windows: RegionToShare is cited as roughly analogous.