improved perfs and event management

src/ui.cpp

@@ -4827,6 +4827,20 @@ void on_activate(GtkApplication* application, gpointer user) {
   gtk_widget_add_controller(app->window, GTK_EVENT_CONTROLLER(press));
 
   gtk_window_present(GTK_WINDOW(app->window));
+
+  // What the window is waiting for, said *before* the first tick. The stream's first CONFIG plans
+  // the buffer on the producer thread, which holds the model's mutex for the whole of it -- at a few
+  // gigabytes that is around a second per gigabyte, and the frame tick cannot read the model while
+  // it runs, so the window does not change. Set here it is on screen already: the present paints a
+  // frame before any timeout fires, which is the difference between waiting and "the dialog
+  // disappeared and nothing happened".
+  if (app->waveform_name.empty()) {
+    const Config& cfg = app->model->config();
+    char buf[192];
+    std::snprintf(buf, sizeof(buf), "connecting to %s:%u -- planning the %.0f MB buffer",
+                  cfg.server.c_str(), unsigned(cfg.port), cfg.buffer_mb);
+    set_notice(*app, buf, 6);
+  }
 }
 
 /// Headless self-check, step 2: read the panel geometry while the widgets still