ui: the signal list is the signals slide-over page, opened by a + badge or g

src/ui_app.hpp

@@ -156,6 +156,7 @@ struct BadgeBar {
   GtkWidget* system_slot = nullptr;   ///< right: Trigger, Source
   Badge trigger;
   Badge source;                       ///< opens the first source page; a read-out when the source has none
+  Badge plus;                         ///< the "+" in the signals slot: opens the `signals` page
 };
 
 struct App {
@@ -253,8 +254,8 @@ struct App {
   GtkWidget* trigger_panel = nullptr;
   GtkWidget* signal_panel = nullptr;
   GtkWidget* side_box = nullptr;
-  /// The dock: the sidebar's one scroller and the box inside it, which holds the signal list, the
-  /// cursors and the measurements (`dock_show_section()` scrolls it). A feature's own on/off never
+  /// The dock: the sidebar's one scroller and the box inside it, which holds the cursors and
+  /// the measurements (`dock_show_section()` scrolls it). A feature's own on/off never
   /// removes a section (it sets its panel's sensitivity instead).
   GtkWidget* dock_page = nullptr;
   GtkWidget* dock_scroller = nullptr;