attempt to remember position when loading history

lib/controllers/room_chat_controller.dart

@@ -39,7 +39,9 @@ class RoomChatController extends AsyncNotifier<IList<Event>> {
     }
 
     return room.timeline
-        .toValueIList(sort: true, compare: (a, b) => (a ?? 0).compareTo(b ?? 0))
+        .toEntryIList(compare: (a, b) => (a?.key ?? 0).compareTo(b?.key ?? 0))
+        .map((element) => element.value)
+        .toIList()
         .addAll(room.sticky)
         .map((entry) {
           final foundEvent = entry == null ? null : room.events[entry];

lib/widgets/room_chat.dart

@@ -79,6 +79,13 @@ class RoomChat extends HookConsumerWidget {
     final scrollController = useScrollController();
     final controllerData = ref.watch(controllerProvider);
 
+    final heightBeforeLoad = useState<double?>(null);
+
+    Future<void> loadOlder() async {
+      heightBeforeLoad.value = scrollController.position.maxScrollExtent;
+      await notifier.loadOlder();
+    }
+
     useEffect(() {
       WidgetsBinding.instance.addPostFrameCallback((_) {
         if (scrollController.hasClients) {
@@ -90,8 +97,19 @@ class RoomChat extends HookConsumerWidget {
     }, [scrollController.hasClients]);
 
     useEffect(() {
-      if (scrollController.hasClients &&
+      if (!scrollController.hasClients || controllerData is! AsyncData) return;
-          scrollController.position.atEdge &&
+
+      if (heightBeforeLoad.value != null) {
+        WidgetsBinding.instance.addPostFrameCallback((_) {
+          if (scrollController.hasClients) {
+            scrollController.jumpTo(
+              scrollController.position.maxScrollExtent -
+                  heightBeforeLoad.value!,
+            );
+          }
+          heightBeforeLoad.value = null;
+        });
+      } else if (scrollController.position.atEdge &&
           scrollController.position.pixels != 0) {
         WidgetsBinding.instance.addPostFrameCallback((_) {
           if (scrollController.hasClients) {
@@ -104,7 +122,9 @@ class RoomChat extends HookConsumerWidget {
 
     useEffect(() {
       Future<void> listener() async {
-        if (!scrollController.position.atEdge) return;
+        if (!scrollController.hasClients || !scrollController.position.atEdge) {
+          return;
+        }
 
         final room = ref.watch(
           RoomsController.provider.select((value) => value[roomId]),
@@ -112,7 +132,9 @@ class RoomChat extends HookConsumerWidget {
         if (room == null) return;
 
         if (scrollController.position.pixels == 0) {
-          if (room.hasMore) await notifier.loadOlder();
+          if (room.hasMore) {
+            await loadOlder();
+          }
         } else {
           await client.markRead(room);
         }
@@ -369,7 +391,7 @@ class RoomChat extends HookConsumerWidget {
                               child: Center(
                                 child: ElevatedButton(
                                   onPressed: controllerData is AsyncData
-                                      ? notifier.loadOlder
+                                      ? loadOlder
                                       : null,
                                   child: Text("Load More"),
                                 ),