Fix unbounded event buffer growth

The setup receiver outlived setup with a frozen index, pinning every
subsequent event in the buffer for the App lifetime. Scope it to
InstallTerminalInfo.

Author: ArthurSonzogni

CHANGELOG.md

@@ -8,6 +8,9 @@ Next
 - Bugfix: `App::PostEvent` is now thread safe again, as documented. Since the
   7.0.0 event loop rework it pushed into an unsynchronized buffer, racing with
   the main loop when called from another thread.
+- Bugfix: Fix unbounded memory growth in the event buffer. A receiver used
+  during terminal setup was kept for the whole `App` lifetime, retaining every
+  subsequent event (including every mouse move).
 
 ### Dom
 - Performance: `text` computes its requirement once and renders only the

src/ftxui/component/app.cpp

@@ -245,7 +245,6 @@ struct App::Internal {
   ThrottledRequest cursor_position_request;
 
   MultiReceiverBuffer<Event> event_buffer;
-  std::unique_ptr<MultiReceiverBuffer<Event>::Receiver> setup_receiver;
   std::unique_ptr<MultiReceiverBuffer<Event>::Receiver> main_loop_receiver;
 
   Internal(App* app, AppDimension dimension, bool use_alternative_screen);
@@ -561,7 +560,6 @@ App::Internal::Internal(App* app,
       cursor_position_request(this, [this] {
         TerminalSend(DeviceStatusReport(DSRMode::kCursor));
       }) {
-  setup_receiver = event_buffer.CreateReceiver();
   main_loop_receiver = event_buffer.CreateReceiver();
 }
 
@@ -1182,6 +1180,10 @@ void App::Internal::InstallTerminalInfo() {
 
   // Wait for the cursor shape reply using the setup head.
   if (is_stdin_a_tty_ && is_stdout_a_tty_) {
+    // A receiver scoped to the setup: keeping one alive after setup would pin
+    // every subsequent event in the buffer, growing it for the whole app
+    // lifetime.
+    auto setup_receiver = event_buffer.CreateReceiver();
     auto start = std::chrono::steady_clock::now();
     bool terminal_capabilities_received = false;
     // Wait for the cursor shape reply using the setup head.