Centralize retained message dialog close callbacks

docs/modernization/roadmap.md

@@ -498,6 +498,8 @@ outside-click close handling now shares the same retained release/remove/
 callback helper.
 About, changelog, settings, and user-manual close buttons now share retained
 destroy-on-click binding through the same overlay service.
+Message-box submit/cancel and input-box cancel destroy callbacks now use the
+same retained close binding helpers.
 Raw popup callback captures and full close/capture ownership remain part of
 `DEBT-0063`.
 `pano_cli inspect-image` exposes PNG IHDR metadata as JSON,