Why the apps that hide windows stopped working on macOS 15

For years, the standard way to make a window invisible to screen sharing was a single flag: tell the OS "don't include this window in captures." A wave of small Mac utilities was built on it. On macOS 15, that trick quietly stopped being reliable — and most of those apps haven't told their users.

The old trick

AppKit exposed a per-window flag (window sharing type / content-protection) that asked the system to exclude a window from screen recordings and shares. Set it, and screen-capture tools were supposed to skip that window. Simple, and for a long time it mostly worked.

What changed

Modern screen sharing on macOS runs through ScreenCaptureKit, and on recent macOS it increasingly captures the fully composited framebuffer — the final image the display shows — rather than compositing window-by-window with per-window exclusion honored. When that happens, a window's "don't capture me" flag can be ignored, because by the time the frame exists, your "hidden" window is already painted into it.

Crucially, Apple provides no public, guaranteed "prevent this window from being captured" API. The old behavior was always more of a courtesy than a contract — and macOS 15 is where a lot of people discovered that the hard way.

Why this matters for a privacy tool

If your screen-privacy app depends on window-exclusion flags, its core promise can silently fail after an OS update — the worst possible failure mode for something you trust with confidential information. You'd never know until the wrong window showed up on a recorded call.

The approach that's durable

ScreenVeil doesn't try to make your real windows invisible to the capture. It composes a separate, curated feed — a clean shared surface built from only what you choose to show — and that's what you hand to Zoom, Meet, Teams, Loom, or OBS. Your private apps aren't "flagged as hidden" on the real screen; they're simply never part of the feed you share in the first place.

That's a different architecture, and it's why it keeps working across the macOS changes that broke the window-exclusion crowd. Not a trick against the capture pipeline — a clean feed that never contained your secrets to begin with.