Regression: Scrolling on threads (#28298)

apps/meteor/client/views/room/contextualBar/Threads/components/ThreadMessageList.tsx

@@ -68,9 +68,8 @@ const ThreadMessageList = ({ mainMessage }: ThreadMessageListProps): ReactElemen
 		<div
 			className={['thread-list js-scroll-thread', hideUsernames && 'hide-usernames'].filter(isTruthy).join(' ')}
 			style={{ scrollBehavior: 'smooth' }}
-			onScroll={handleScroll}
 		>
-			<ScrollableContentWrapper ref={listWrapperScrollRef}>
+			<ScrollableContentWrapper ref={listWrapperScrollRef} onScroll={handleScroll}>
 				<ul className='thread' ref={listRef}>
 					{loading ? (
 						<li className='load-more'>

apps/meteor/client/views/room/contextualBar/Threads/hooks/useLegacyThreadMessageListScrolling.ts

-import type { UIEvent } from 'react';
+import type { ScrollValues } from 'rc-scrollbars';
 import { useCallback, useEffect, useRef } from 'react';
 
 export const useLegacyThreadMessageListScrolling = () => {
@@ -7,8 +7,8 @@ export const useLegacyThreadMessageListScrolling = () => {
 
 	const atBottomRef = useRef(true);
 
-	const onScroll = useCallback(({ currentTarget: e }: UIEvent) => {
-		atBottomRef.current = e.scrollTop >= e.scrollHeight - e.clientHeight;
+	const onScroll = useCallback(({ scrollHeight, scrollTop, clientHeight }: ScrollValues) => {
+		atBottomRef.current = scrollTop >= scrollHeight - clientHeight;
 	}, []);
 
 	const sendToBottomIfNecessary = useCallback(() => {