Unify event handling behavior for all cases

This makes the individual plugin host slightly more complex, but now
both individually hosted plugins and plugin groups handle both
dispatcher events and GUI events in the exact same way.

src/wine-host/bridges/group.cpp

@@ -128,7 +128,7 @@ void GroupBridge::handle_plugin_dispatch(const GroupRequest request) {
 
     // Blocks this thread until the plugin shuts down, handling all events on
     // the main IO context
-    bridge->handle_dispatch_multi(plugin_context);
+    bridge->handle_dispatch();
     logger.log("'" + request.plugin_path + "' has exited");
 
     // After the plugin has exited, we'll remove this thread's plugin from the
@@ -214,8 +214,8 @@ void GroupBridge::accept_requests() {
             logger.log("Received request to host '" + request.plugin_path +
                        "' using socket '" + request.socket_path + "'");
             try {
-                auto bridge = std::make_unique<Vst2Bridge>(request.plugin_path,
-                                                           request.socket_path);
+                auto bridge = std::make_unique<Vst2Bridge>(
+                    plugin_context, request.plugin_path, request.socket_path);
                 logger.log("Finished initializing '" + request.plugin_path +
                            "'");
 
@@ -261,6 +261,8 @@ void GroupBridge::async_handle_events() {
         // TODO: Check if those same weird crashes with Serum are happening
         //       again with these normal threads
         if (!should_skip_message_loop()) {
+            std::lock_guard lock(active_plugins_mutex);
+
             MSG msg;
 
             // Keep the loop responsive by not handling too many events at once