Implement the plugin side if IComponentHandler3

src/plugin/bridges/vst3-impls/plugin-proxy.cpp

@@ -39,6 +39,26 @@ Vst3PluginProxyImpl::queryInterface(const Steinberg::TUID _iid, void** obj) {
     return result;
 }
 
+size_t Vst3PluginProxyImpl::register_context_menu(
+    Steinberg::IPtr<Steinberg::Vst::IContextMenu> menu) {
+    std::lock_guard lock(context_menus_mutex);
+
+    const size_t context_menu_id = current_context_menu_id.fetch_add(1);
+    context_menus.emplace(context_menu_id, std::move(menu));
+
+    return context_menu_id;
+}
+
+/**
+ * Unregister a context menu using the ID generated by a previous call to
+ * `register_context_menu()`. This will release the context menu object
+ * returned by the host.
+ */
+bool Vst3PluginProxyImpl::unregister_context_menu(size_t context_menu_id) {
+    std::lock_guard lock(context_menus_mutex);
+    return context_menus.erase(context_menu_id);
+}
+
 tresult PLUGIN_API Vst3PluginProxyImpl::setAudioPresentationLatencySamples(
     Steinberg::Vst::BusDirection dir,
     int32 busIndex,
@@ -373,6 +393,7 @@ tresult PLUGIN_API Vst3PluginProxyImpl::setComponentHandler(
         // Automatically converted smart pointers for when the plugin performs a
         // callback later
         component_handler_2 = component_handler;
+        component_handler_3 = component_handler;
         unit_handler = component_handler;
 
         return bridge.send_message(YaEditController::SetComponentHandler{