ui: the sidebar's tabs become one dock; Measure and Signals by keyboard section; session keeps the dock's state

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

src/ui_app.hpp

@@ -241,13 +241,11 @@ struct App {
   GtkWidget* trigger_panel = nullptr;
   GtkWidget* signal_panel = nullptr;
   GtkWidget* side_box = nullptr;
-  /// The sidebar's tab stack and its switcher. The stack is what chooses which panels are on
-  /// screen; a feature's own on/off never does (it sets its panel's sensitivity instead).
-  GtkWidget* side_stack = nullptr;
-  GtkWidget* side_switcher = nullptr;
-  /// The page name the stack is showing, and the one value the session file persists about the
-  /// sidebar. "signals" on a first run.
-  std::string side_tab = "signals";
+  /// 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
+  /// removes a section (it sets its panel's sensitivity instead).
+  GtkWidget* dock_page = nullptr;
+  GtkWidget* dock_scroller = nullptr;
   GtkWidget* arm_button = nullptr;
   /// The Force button, beside the Arm/Disarm one: one acquisition now, with the configured pre/post
   /// window. It carries no state of its own -- `sync_arm_buttons()` states the one it has
@@ -477,18 +475,6 @@ struct App {
   /// works, and every other line of the dump still passes.
   std::string dbg_toolbar_icons;
   std::string dbg_app_icons;
-  /// What the switcher is: how many pills it holds, and how many labels it is *drawing*. The tabs
-  /// are words (`wide` policy, a title per page), so the label count must equal the page count.
-  int dbg_switcher_pills = -1;
-  int dbg_switcher_labels = -1;
-  /// How many `GtkImage`s the switcher has *mapped*: a tab is its title and nothing else, so this
-  /// must be 0 -- an icon, or the missing-icon placeholder GTK draws for a page with no `icon-name`.
-  int dbg_switcher_images = -1;
-  /// How many pages the sidebar stack holds: `pills` and `labels` must both equal it.
-  int dbg_switcher_pages = -1;
-  /// The switcher's own size, beside it: what the tab bar costs the column.
-  int dbg_switcher_w = -1;
-  int dbg_switcher_h = -1;
   /// The panes' own switches and the header bar's buttons, read together by the exit probe: the two
   /// must agree, and `dbg_panel_drove_toolbar` is the pane's switch having moved the button.
   int dbg_panel_switch_trigger = -1;
@@ -504,7 +490,6 @@ struct App {
   /// The Arm button, read with the trigger off: it is the pane's one runtime control, so it is the one
   /// thing in the body that *is* disabled with the mode.
   int dbg_arm_sensitive = -1;
-  int dbg_switcher_policy = -1;
   /// The header bar, so the dump can report the order the controls are in: a header bar is a
   /// *titlebar*, not a child of the window, so walking down from the window does not reach it.
   GtkWidget* toolbar = nullptr;
@@ -881,7 +866,7 @@ struct App {
   std::string source_kind = "udps";
   SourceConfig source_opts;
   std::string source_title;
-  /// The panels the source kind added to `side_stack`, in tab order. Empty for UDPS and in file mode.
+  /// The panels the source kind added to the slide-over, in page order. Empty for UDPS and in file mode.
   std::vector<SourcePanelPage> source_panels;
   bool source_has_datagrams = true;  ///< the kind reports raw datagrams; false leaves the capture button disabled
   guint layout_save_source = 0;
@@ -1139,7 +1124,14 @@ struct App {
   int dbg_signal_row_h = 0;
   int dbg_trigger_w = 0;
   int dbg_trigger_h = 0;
+  /// The signal list has rows (the dock has no tab to be "current" on any more).
   int dbg_signal_page_current = 0;
+  /// The dock as the exit probe found it: the split view showing the sidebar, the column sensitive (it is
+  /// not until the stream has signals), its width, and how many `GtkScrolledWindow`s it holds directly.
+  int dbg_dock_shown = -1;
+  int dbg_dock_sensitive = -1;
+  int dbg_dock_w = -1;
+  int dbg_dock_scrollers = -1;
   int dbg_trigger_sensitive = 0;
   int dbg_trigger_items = 0;
   int dbg_trigger_selected = -1;
@@ -1161,7 +1153,6 @@ struct App {
   double dbg_trigger_time = 0.0;
   int dbg_trigger_time_valid = -1;
   std::string dbg_mode_live;
-  int dbg_switcher_visible = 0;
   int dbg_trigger_sensitive_default = 0;
 
   /// The detail string the popover and the exit dump read. The dump used to read the label,
@@ -1572,9 +1563,9 @@ constexpr int kEventThumbH = 46;
 constexpr int kEventThumbMaxH = 104;
 inline int g_stats_phase = 0;
 inline std::vector<std::uint64_t> g_stats_n_before;
-/// The same for the tab-switch probe: the accumulator counts recorded while the Measure page was
-/// still current, so the report can say whether any of them advanced afterwards.
-inline std::vector<std::uint64_t> g_side_tab_n_before;
+/// The same for the dock-section probe: the accumulator counts recorded while the Measure section was
+/// still scrolled into view, so the report can say whether any of them advanced after it scrolled out.
+inline std::vector<std::uint64_t> g_dock_section_n_before;
 inline double g_trigrenum_edge = 0.0;
 inline std::uint64_t g_trigrenum_latches = 0;
 inline ConditionProbe g_condition;
@@ -1600,11 +1591,6 @@ void config_dialog_refresh(ConfigDialog& d);
 void open_configurations(App& app);
 void save_layout_now(App& app);
 
-/// The sidebar's tabs are words: hide the icon every `AdwViewSwitcherButton` draws (the
-/// missing-icon placeholder, for a page with a title and no `icon-name`), for the buttons that exist
-/// and for any page added later. Call once, before `build_source_panels()`.
-void keep_tabs_icon_free(App& app);
-
 /// Capability panels (`src/ui_source.cpp`). `build_source_panels` adds the source kind's panels as
 /// pages of the slide-over (`source-<id>`), once, before the first tick. `apply_source_panels` sets every panel's
 /// sensitivity from `connected` -- disabled, never hidden.
@@ -1803,8 +1789,9 @@ void row_menu_fill(RowMenuState& st);
 GtkWidget* open_row_menu(App& app, int row, double x, double y, GtkWidget* parent, bool autohide = true);
 void on_right_click(GtkGestureClick* gesture, int, double x, double y, gpointer user);
 gboolean on_drop_channel(GtkDropTarget*, const GValue* value, double x, double y, gpointer user);
-void on_side_tab_changed(GObject*, GParamSpec*, gpointer user);
-void select_side_tab(App& app, const char* name);
+/// Scrolls the dock to a section: "signals" (the top) or "measure" (the cursors panel, which the
+/// measurements follow). An unknown name is a no-op.
+void dock_show_section(App& app, const char* section);
 /// Reads each pane's own switch back off the header bar's button, and the other way round: the two are
 /// one control in two places, and `panel_switch_sync` keeps the write from looking like a click.
 void sync_panel_switches(App& app);
@@ -1907,8 +1894,9 @@ gboolean measurepin_live_wait(gpointer user);
 gboolean measure_trace(gpointer user);
 gboolean stats_probe_report(gpointer user);
 gboolean stats_probe(gpointer user);
-gboolean side_tab_probe_report(gpointer user);
-gboolean side_tab_probe(gpointer user);
+gboolean dock_section_probe_report(gpointer user);
+gboolean dock_section_probe(gpointer user);
+gboolean dock_session_probe(gpointer user);  // UDPSCOPE_PROBE_DOCK_SESSION_MS
 /// The slide-over panel (`src/ui_slideover.cpp`): one panel at a time over the plot's right edge, a page
 /// per setup surface, each page in a scroller of its own.
 void build_slideover(App& app);  // once, after the plot_overlay exists