chore: deselect events in message overlay dispose function

lib/pages/chat/chat.dart

@@ -1651,6 +1651,13 @@ class ChatController extends State<ChatPageWithRoom>
       showEmojiPicker = false;
     });
   }
+
+  void setSelectedEvent(Event event) {
+    setState(() {
+      selectedEvents.clear();
+      selectedEvents.add(event);
+    });
+  }
   // Pangea#
 
   void clearSingleSelectedEvent() {

lib/pangea/toolbar/widgets/message_selection_overlay.dart

@@ -109,8 +109,19 @@ class MessageOverlayController extends State<MessageSelectionOverlay>
 
   @override
   void initState() {
-    initializeTokensAndMode();
     super.initState();
+    initializeTokensAndMode();
+    WidgetsBinding.instance.addPostFrameCallback(
+      (_) => widget.chatController.setSelectedEvent(event),
+    );
+  }
+
+  @override
+  void dispose() {
+    WidgetsBinding.instance.addPostFrameCallback(
+      (_) => widget.chatController.clearSelectedEvents(),
+    );
+    super.dispose();
   }
 
   Future<void> initializeTokensAndMode() async {

lib/pangea/toolbar/widgets/overlay_header.dart

@@ -36,9 +36,10 @@ class OverlayHeaderState extends State<OverlayHeader> {
   Widget build(BuildContext context) {
     final l10n = L10n.of(context);
     final theme = Theme.of(context);
-    final pinned = controller.room.pinnedEventIds.contains(
-      controller.selectedEvents.first.eventId,
-    );
+    final pinned = controller.selectedEvents.length == 1 &&
+        controller.room.pinnedEventIds.contains(
+          controller.selectedEvents.first.eventId,
+        );
     return Container(
       padding: const EdgeInsets.symmetric(horizontal: 10),
       decoration: BoxDecoration(