stickers replace composer, instead of sending immediately

Fixes #153

lib/controllers/client.dart

@@ -178,25 +178,8 @@ class ClientController extends AsyncNotifier<int> {
   Future<Event> sendMessage(SendMessageRequest request) async =>
       Event.fromJson(await _sendCommand("send_message", request.toJson()));
 
-  Future<Event> sendEvent(SendEventRequest request) async {
-    final json = request.toJson();
-    final content = request.content.toJson();
-
-    return .fromJson(
-      await _sendCommand("send_event", {
-        ...json,
-        "content": {
-          ...content,
-          if (request.relatesTo != null)
-            "m.relates_to": {
-              ...((content["m.relates_to"] as Map<String, dynamic>?) ?? {}),
-              "event_id": request.relatesTo,
-              "rel_type": request.relationType,
-            },
-        },
-      }),
-    );
-  }
+  Future<Event> sendEvent(SendEventRequest request) async =>
+      Event.fromJson(await _sendCommand("send_event", request.toJson()));
 
   Future<String?> setState(SetStateRequest request) async =>
       await _sendCommand("set_state", request.toJson());

lib/controllers/room_chat.dart

@@ -340,7 +340,21 @@ class RoomChatController(final ChatParams info)
     );
   }
 
-  Future<void> sendSticker(String shortcode, PackImage image) async {
+  /// Sends [image] as a sticker, as a reply to [repliedEventRowId] if set.
+  Future<void> sendSticker(
+    String shortcode,
+    PackImage image, {
+    bool shouldMention = true,
+    int? repliedEventRowId,
+  }) async {
+    final repliedEvent = repliedEventRowId == null
+        ? null
+        : ref.read(
+            RoomsController.provider.select(
+              (rooms) => rooms[info.roomId]?.events[repliedEventRowId],
+            ),
+          );
+
     final event = await ref
         .read(ClientController.provider.notifier)
         .sendEvent(
@@ -352,6 +366,12 @@ class RoomChatController(final ChatParams info)
               info: image.info ?? const .new(),
               url: image.url,
             ),
+            mentions: Mentions(
+              userIds: [
+                if (shouldMention && repliedEvent != null) repliedEvent.sender,
+              ].toIList(),
+            ),
+            replyTo: repliedEvent?.eventId,
           ),
         );