Base codebehind for JRGroup, the parent of every sub-panel / dialog (and, transitively, every JRScreen). Kept intentionally minimal: it exists only to provide the onDestroy() floor below.

Floor for JRGroup subclasses (panels/dialogs) that DON'T override onDestroy(): abandon any pending fetchAsync promises so a late pool response can't fire a callback into the destroyed node. A subclass that overrides onDestroy() and calls fetchAsync gets this from the auto-abandon-promises BSC plugin, which injects abandonApiPromises() into its own onDestroy. SG component onDestroy does not chain to this base, so the call can't rely on inheritance alone.