ui: the readouts strip hides when there are no cursors or measurements

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

src/ui_probe.cpp

@@ -4339,9 +4339,10 @@ static int dock_width_fits(App& a, int* dock_w, int* side_w) {
 
 /// The readouts strip against the dock it mirrors: `same_text=1` when every strip label's text equals the
 /// dock's (the cursors' `who` and delta cells, the measurements' values) and the counts agree. The strip is
-/// shown whenever the dock is not beside the plot, so `expected` is `!dock_shown || collapsed` (`dock_shown`
-/// is `show-sidebar`, `collapsed` the split view's, both read in the same frame as `visible`), `visible_ok`
-/// is `visible == expected`, and `h` is the strip's fixed 26 whenever it is visible.
+/// shown whenever the dock is not beside the plot and there is something to read, so `expected` is
+/// `(!dock_shown || collapsed) && (cursors on || a measurement)` (`dock_shown` is `show-sidebar`, `collapsed`
+/// the split view's, both read in the same frame as `visible`), `visible_ok` is `visible == expected`, and
+/// `h` is the strip's fixed 26 whenever it is visible.
 /// `sens_same` is the strip's cursor chips sharing the dock grid's sensitivity.
 static void strip_report(App& a, const char* tag, const char* what) {
   const auto text = [](GtkWidget* w) { return std::string(gtk_label_get_text(GTK_LABEL(w))); };
@@ -4365,19 +4366,35 @@ static void strip_report(App& a, const char* tag, const char* what) {
   const bool collapsed =
       a.side_view != nullptr &&
       adw_overlay_split_view_get_collapsed(ADW_OVERLAY_SPLIT_VIEW(a.side_view)) != FALSE;
-  const bool expected = !dock_shown || collapsed;
+  // And with something to read: the cursors on, or a measurement (`sync_readouts_strip()`).
+  const bool has_content =
+      (a.cursors_toggle != nullptr &&
+       gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(a.cursors_toggle))) ||
+      !a.measures.empty();
+  const bool expected = (!dock_shown || collapsed) && has_content;
   const bool sens_same =
       a.strip_cursor_box != nullptr && a.dock_cursor_grid != nullptr &&
       gtk_widget_get_sensitive(a.strip_cursor_box) == gtk_widget_get_sensitive(a.dock_cursor_grid);
+  // `groups=<cursors><measures><separator>`: which sections of the strip are shown, each against its own
+  // feature (cursors on, a measurement present, both); `groups_ok=1` when all three agree.
+  const bool cur_on = a.cursors_toggle != nullptr &&
+                      gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(a.cursors_toggle));
+  const bool mea_on = !a.measures.empty();
+  const bool g_cur = a.strip_cursor_group != nullptr && gtk_widget_get_visible(a.strip_cursor_group);
+  const bool g_mea = a.strip_measure_group != nullptr && gtk_widget_get_visible(a.strip_measure_group);
+  const bool g_sep = a.strip_sep != nullptr && gtk_widget_get_visible(a.strip_sep);
+  const bool groups_ok = g_cur == cur_on && g_mea == mea_on && g_sep == (cur_on && mea_on);
   std::fprintf(stderr,
                "[%s-probe] %-14s strip: visible=%d expected=%d visible_ok=%d dock_shown=%d cursors=%zu "
-               "measures=%zu same_text=%d h=%d sens_same=%d collapsed=%d window=%d\n",
+               "measures=%zu same_text=%d h=%d sens_same=%d collapsed=%d window=%d groups=%d%d%d "
+               "groups_ok=%d\n",
                tag, what, visible ? 1 : 0, expected ? 1 : 0, visible == expected ? 1 : 0,
                dock_shown ? 1 : 0, a.strip_cursor_deltas.size(),
                a.strip_measure_labels.size(), same, a.readouts_strip != nullptr
                    ? gtk_widget_get_height(a.readouts_strip) : -1,
                sens_same ? 1 : 0, collapsed ? 1 : 0,
-               a.window != nullptr ? gtk_widget_get_width(a.window) : -1);
+               a.window != nullptr ? gtk_widget_get_width(a.window) : -1,
+               g_cur ? 1 : 0, g_mea ? 1 : 0, g_sep ? 1 : 0, groups_ok ? 1 : 0);
 }
 
 /// Puts the dock away through the wish the tick re-asserts and reads the strip with it hidden
@@ -4761,6 +4778,9 @@ gboolean measures_probe_step(gpointer user) {
         std::fprintf(stderr, "[measures-probe] no acquired signal to measure\n");
         return G_SOURCE_REMOVE;
       }
+      // The "neither" state: no measurement yet and (from a fresh config) the cursors off, so the strip is
+      // hidden -- `visible=0 expected=0 groups=000`. (The other readings need a state with something in it.)
+      strip_report(*a, "measures", "start");
       for (int i = 0; i < measure_type_count(); ++i) {
         Measure m;
         m.signal = signal;