## Summary On the LG MyView 34SR60QC (3440×1440, 21:9, webOS 23/24), built-in streaming apps render 21:9 content inside a fixed 16:9 container, producing black bars on all four sides. The on-screen Aspect Ratio menu is greyed out while these apps run, and I can find no sanctioned API — SSAP or Luna — that a third-party app or a Developer Mode session can use to adjust the picture scaler. I’d like to know the intended path, or request one. ## Hardware / firmware - Model: LG MyView 34SR60QC (3440×1440, 21:9 curved) - webOS 23/24 (smart monitor build) — firmware: ## The problem (user-visible) - Apps such as JioHotstar deliver 21:9 films inside a 16:9 frame. On a 21:9 panel the 16:9 frame is pillarboxed and the film is letterboxed inside it, giving black bars on all four sides. - The monitor’s Aspect Ratio menu is greyed out while these apps are in the foreground, so the user cannot zoom from the remote either. - External HDMI inputs are unaffected (aspect controls work there). For the built-in apps there is no remedy. ## What I tested (developer level) I built an SSAP client (standard com.lge.test manifest, PROMPT pairing). Read access works; every write to the picture/scaler settings is denied: | Attempt | Result | |—|—| | PROMPT pairing, getForegroundAppInfo, listLaunchPoints | Works | | ssap://settings/setSystemSettings (direct) | 401 insufficient permissions | | ssap://settings/getSystemSettings (category “aspectRatio”) | 500 — category aspectRatio doesn’t support the key(s): arcPerApp, justScan | | createAlert → onclose → luna://com.webos.settingsservice/setSystemSettings | 401 insufficient permissions | | Developer Mode SSH, /usr/bin/luna-send | mode 700 root:root → “Permission denied” | | Developer Mode SSH, /usr/bin/luna-send-pub, getSystemSettings | {“returnValue”:false,“errorText”:“Access denied”} | | Developer Mode prisoner identity | uid=6989 groups=audio,video,compositor,se,crashd | So settingsservice (read and write) appears gated behind a private-bus ACG that neither a PROMPT-paired app nor the Developer Mode prisoner account holds. The 500 also shows the TV-era key names (arcPerApp/justScan) are not valid on this monitor’s aspectRatio category, and I cannot query the correct schema without that same privilege. ## What I’m asking Any one of these would resolve it: 1. A sanctioned API (public-bus Luna method or an SSAP endpoint) that a paired app or a Developer Mode app can use to set aspect ratio / scaler mode, even if limited to a per-app or per-input scope. 2. A firmware fix so built-in apps on 21:9 smart monitors expose a correct 21:9 viewport (or at least honor a zoom/crop) instead of a hardcoded 16:9 container. 3. At minimum, keep the on-screen Aspect Ratio menu usable while these apps run, so users can zoom manually from the remote. I can share full request/response logs and getSystemSettings output, and I’m happy to test a suggested method on the device. Thanks.