ui: draw the sidebar tabs without the placeholder icon

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

src/ui.cpp

@@ -3060,8 +3060,11 @@ void note_panel_controls(App& app) {
   // pill count reads 0 and the label count means nothing, rather than passing vacuously.
   int pills = 0;
   int drawn_labels = 0;
+  int drawn_images = 0;
   const std::function<void(GtkWidget*)> count_drawn = [&](GtkWidget* w) {
     if (GTK_IS_TOGGLE_BUTTON(w) && gtk_widget_get_mapped(w)) ++pills;
+    // A *mapped* image is an icon (or its missing-icon placeholder) on a tab: tabs are words only.
+    if (GTK_IS_IMAGE(w) && gtk_widget_get_mapped(w)) ++drawn_images;
     // A *mapped* label with text: an empty label would be counted by "mapped" alone.
     if (GTK_IS_LABEL(w) && gtk_widget_get_mapped(w) && gtk_label_get_text(GTK_LABEL(w))[0] != '\0') {
       ++drawn_labels;
@@ -3074,6 +3077,7 @@ void note_panel_controls(App& app) {
   if (app.side_switcher != nullptr) count_drawn(app.side_switcher);
   app.dbg_switcher_pills = pills;
   app.dbg_switcher_labels = drawn_labels;
+  app.dbg_switcher_images = drawn_images;
   // Walked through `get_pages()`, not the widget tree: an `AdwViewStackPage` is a plain `GObject`.
   app.dbg_switcher_pages =
       app.side_stack != nullptr
@@ -5203,7 +5207,9 @@ void on_activate(GtkApplication* application, gpointer user) {
                      G_CALLBACK(on_side_tab_changed), app);
   }
   // The source kind's own tabs (a generator, digital I/O), added before the first tick so the
-  // pages-versus-pills reading below counts them too.
+  // pages-versus-pills reading below counts them too. The tabs are words, so the switcher's icons
+  // are hidden first and kept hidden for the pages this call adds.
+  keep_tabs_icon_free(*app);
   build_source_panels(*app);
 
   // The left side is the events pane *and* the plot, in one row: the pane is a column of its own
@@ -6240,10 +6246,10 @@ int run_ui(int argc, char** argv, const Config& cfg, ScopeModel& model, Acquisit
                 app.dbg_panel_switch_trigger, app.dbg_toolbar_switch_trigger,
                 app.dbg_panel_switch_cursors, app.dbg_toolbar_switch_cursors,
                 app.dbg_panel_drove_toolbar);
-    std::printf("[udpscope]   switcher: policy=%s pills=%d labels=%d pages=%d size=%dx%d\n",
+    std::printf("[udpscope]   switcher: policy=%s pills=%d labels=%d images=%d pages=%d size=%dx%d\n",
                 app.dbg_switcher_policy == 0 ? "narrow" : (app.dbg_switcher_policy == 1 ? "wide" : "?"),
-                app.dbg_switcher_pills, app.dbg_switcher_labels, app.dbg_switcher_pages,
-                app.dbg_switcher_w, app.dbg_switcher_h);
+                app.dbg_switcher_pills, app.dbg_switcher_labels, app.dbg_switcher_images,
+                app.dbg_switcher_pages, app.dbg_switcher_w, app.dbg_switcher_h);
     // The help affordance layer: what the contextual-help toggle left on the surfaces, and where the
     // guided tour stood when the last capture ran. Both are captured on the tick (`capture_help_state`),
     // so neither asks a destroyed widget anything.