ui: reword the docs that still spoke of the list drag; keep disabled signals' badge order; stamp the signal generation before the snapshot

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/ui/signals-panel.ui

@@ -53,7 +53,7 @@
         <property name="spacing">6</property>
         <child>
           <object class="GtkLabel" id="signals_hint">
-            <property name="label" translatable="yes">drag a signal onto a plot</property>
+            <property name="label" translatable="yes">click a signal for its page; drag its badge onto a plot</property>
             <property name="halign">start</property>
             <property name="hexpand">1</property>
             <property name="css-classes">dim-label</property>

src/ui_badges.cpp

@@ -102,14 +102,23 @@ gboolean on_badge_drop(GtkDropTarget*, const GValue* value, double, double, gpoi
   if (prev != moved->button) {  // already directly in front: nothing to move
     gtk_box_reorder_child_after(GTK_BOX(app->badges.signals_row), moved->button, prev);
   }
-  // The order, as the widgets now stand.
-  app->badge_order.clear();
+  // The order, as the widgets now stand; the names that are not shown (signals switched off) keep their old
+  // relative order after the visible ones, so switching one back on finds it where it was remembered.
+  std::vector<std::string> order;
   for (GtkWidget* c = gtk_widget_get_first_child(app->badges.signals_row); c != nullptr;
        c = gtk_widget_get_next_sibling(c)) {
     for (auto& b : app->badges.signal_badges) {
-      if (b->button == c) app->badge_order.push_back(b->signal_name);
+      if (b->button == c) order.push_back(b->signal_name);
     }
   }
+  const std::size_t shown_count = order.size();
+  for (const std::string& n : app->badge_order) {
+    if (std::find(order.begin(), order.begin() + static_cast<std::ptrdiff_t>(shown_count), n) ==
+        order.begin() + static_cast<std::ptrdiff_t>(shown_count)) {
+      order.push_back(n);
+    }
+  }
+  app->badge_order = std::move(order);
   return TRUE;
 }
 

src/ui_signals.cpp

@@ -569,6 +569,9 @@ void rebuild_signal_panels(App& app) {
   // GTK calls (a use-after-free of the name strings otherwise).
   std::vector<SignalInfo> signals;
   bool have_signals = false;
+  // The generation this build answers to is read *before* the snapshot: a CONFIG landing between the two
+  // would otherwise be stamped as seen without having been, and the tick would never rebuild for it.
+  const unsigned generation = app.model->generation();
   {
     std::lock_guard<std::mutex> lock(app.model->mutex());
     signals = app.model->signals();
@@ -585,7 +588,7 @@ void rebuild_signal_panels(App& app) {
   }
   signal_pages_sync(app);
   sync_signal_badges(app);
-  app.signal_generation = app.model->generation();
+  app.signal_generation = generation;
 }
 
 GtkWidget* build_signal_panel(App& app) {