fix: the [edit] buttons' icons, and the locked pane says four lines not one

Two things the lock shipped wrong.

**The "done" icon did not exist.** `emblem-ok-symbolic` is a breeze icon; Adwaita — which is what this
app runs under — does not have it, so the button that leaves configuration mode drew a missing-image
placeholder, i.e. nothing. Both names are now Adwaita's own: `document-edit-symbolic` (the pencil: edit)
and `object-select-symbolic` (the check: done). This is exactly the silent failure `toolbar icons:`
exists for, so the two `[edit]` buttons get the same treatment: `pane edits: locked=…(ok) config=…(ok)`
is read by clicking into configuration mode and back, so one line carries both names and
`gtk_icon_theme_has_icon()`'s verdict for each. The invariants now carry the rule, including the trap
that a name found under `breeze` is not an answer.

**The locked pane was too compact.** One line could not hold what a user opens the pane for, so it is now
a small definition list: `signal`, `condition`, `level`, `mode` on four lines, and after that only the
figures that are *not* at their defaults — `noise band`, `HF reject`, `pre-trigger`, `hold-off` — because
a line reading "band 0" is a line that says nothing. The channel is resolved from the acquired channels
and the condition quotes the figures its own shape reads (a width and its comparison, two levels, or a
timeout), never one it ignores. The pane is ~192 px tall locked against 580 in configuration mode.

One self-inflicted critical on the way: the probe read the summary with `gtk_label_get_text()`, and the
container is a grid now — `Gtk-CRITICAL: assertion 'GTK_IS_LABEL (self)' failed`. The text comes from the
sync that writes it instead.

Verified: `pane edits: locked=document-edit-symbolic(ok) config=object-select-symbolic(ok)`;
`panes: trigger=locked signals=locked body_visible=0 summary='signal: square | condition: window, falling
| level: 0.3 .. 0.6 | mode: single | noise band: 0.2 | pre-trigger: 20 % | hold-off: 1000 ms'`;
`make test-ui` 14 files; zero `Gtk-CRITICAL` and no missing icon.

docs/claude/invariants-gtk-and-chrome.md

@@ -184,6 +184,13 @@ Part of [CLAUDE.md](../../CLAUDE.md). These are rules that cost a defect to lear
   **tooltip and accessible name** from the page's name, then hides the empty label that would otherwise
   leave the icon off-centre. An icon-only pill is still a named control for a screen reader, and
   `switcher: … pills=2 labels=0 names=2` is the reading for all three facts at once.
+- **A stock icon name has to be one *Adwaita* has, and a blank button is the failure mode.** The two
+  panes' `[edit]` buttons are `document-edit-symbolic` (the pencil: edit) and `object-select-symbolic`
+  (the check: done). The done one was `emblem-ok-symbolic`, which breeze ships and **Adwaita does not** —
+  so the button that leaves configuration mode was blank, which no other reading could see: the button
+  worked, the layout was unchanged, and only `pane edits:` (the two names and
+  `gtk_icon_theme_has_icon()`'s verdict, clicked into each mode) would say so. Check a name against
+  `/usr/share/icons/Adwaita` before using it; a name found under `breeze` is not an answer.
 - **A pane's heading switch and the header bar's button are one control in two places.** Each pane's
   heading (`build_trigger_panel()` builds the trigger's, `cursors-panel.ui` has the cursors' in its
   `head`) carries a `GtkSwitch` that runs the *same action* the toolbar button runs, and

docs/claude/probe-readings.md

@@ -1142,22 +1142,32 @@ library measures and draws the rect in tests of its own.
 ## `panes:` — the locked and configuration modes
 
 ```
-[udpscope]   panes: trigger=locked signals=locked body_visible=0 summary='window · square · 0.25…0.5 · 20 % pre'
+[udpscope]   pane edits: locked=document-edit-symbolic(ok) config=object-select-symbolic(ok)
+[udpscope]   panes: trigger=locked signals=locked body_visible=0 summary='signal: square | condition: window, falling | level: 0.3 .. 0.6 | mode: single | noise band: 0.2 | pre-trigger: 20 % | hold-off: 1000 ms'
 [udpscope]   panes: trigger=config signals=config body_visible=1 summary=''
 ```
 
+**`pane edits:`** is the two `[edit]` buttons in each mode, by name and verdict, and it exists because of
+a real defect: the "done" icon was `emblem-ok-symbolic`, which **Adwaita does not have** (breeze does), so
+the button that leaves configuration mode was blank — and a blank icon button is invisible in every other
+reading, exactly as `toolbar icons:` describes for the toolbar. The probe clicks into configuration mode
+and back, so one line carries both names. **Both must read `(ok)`**, and the pair is
+`document-edit-symbolic` (the pencil: edit) and `object-select-symbolic` (the check: done).
+
 Both panes have two modes. **Locked** is what a returning user gets — the trigger pane shows the one line
 in `summary`, the signal list shows only the signals that are on, and neither offers a control that
 changes the configuration — and **config** is the full pane, which is what a *first run* gets, because a
 session file that loaded is what "we have been here before" means. Each heading's `[edit]` button flips
 its pane.
 
-- **`summary`** is the locked trigger pane's whole content, so it is read rather than assumed: empty here
-  is a locked pane showing nothing at all. It quotes the shape, the channel, the figures that shape
-  actually reads (a level, two levels, a width plus its comparison, or a timeout) and the pre-trigger
-  share — never a figure the shape ignores.
-- **`body_visible=0`** is the settings being off screen, which is what makes the pane 42 px tall instead
-  of 580 in `panels:`.
+- **`summary`** is the locked trigger pane's whole content, as `key: value` pairs separated by ` |`. The
+  pane draws it as a small definition list — `signal`, `condition`, `level`, `mode` on four lines, and
+  then only the figures that are *not* at their defaults (`noise band`, `HF reject`, `pre-trigger`,
+  `hold-off`), because a line reading "band 0" is a line that says nothing. One line was tried first and
+  was too little: the four answers are what a user opens the pane for. `summary=''` with
+  `body_visible=0` is a locked pane showing nothing at all, which is the defect this reads for.
+- **`body_visible=0`** is the settings being off screen, which is what makes the pane a couple of hundred
+  pixels instead of 580 in `panels:`.
 - **The locked signal list drops the rows of the signals that are off**, so `rows` counts what is on:
   `signals panel: … rows=3 signals=2 divider=1` is two on signals and the `MATH` divider, not four
   signals. Its `+` goes with them — a `+` on a locked list opens the editor the lock exists to keep shut.

src/ui.cpp

@@ -4410,8 +4410,11 @@ void apply_pane_lock(App& app) {
   }
   const auto edit_button = [](GtkWidget* button, bool locked, const char* what) {
     if (button == nullptr) return;
+    // Both names must be ones Adwaita *has*: `emblem-ok-symbolic` exists only in breeze, so the "done"
+    // button was blank -- and a blank icon button is invisible in every other reading, which is why
+    // `pane edits:` checks these two by name and verdict.
     gtk_button_set_icon_name(GTK_BUTTON(button),
-                             locked ? "emblem-system-symbolic" : "emblem-ok-symbolic");
+                             locked ? "document-edit-symbolic" : "object-select-symbolic");
     const std::string tip = std::string(locked ? "configure " : "keep this configuration of ") + what;
     gtk_widget_set_tooltip_text(button, tip.c_str());
   };
@@ -5775,6 +5778,14 @@ int run_ui(int argc, char** argv, const Config& cfg, ScopeModel& model, Acquisit
                 app.dbg_trigger_sensitive, app.dbg_switcher_visible,
                 rows.cursors_visible() ? 1 : 0, rows.time_window(),
                 app.window_limit_s);
+    {
+      GtkIconTheme* theme = gtk_icon_theme_get_for_display(gdk_display_get_default());
+      std::printf("[udpscope]   pane edits: locked=%s(%s) config=%s(%s)\n",
+                  app.dbg_pane_edit_icon.c_str(),
+                  gtk_icon_theme_has_icon(theme, app.dbg_pane_edit_icon.c_str()) ? "ok" : "MISSING",
+                  app.dbg_pane_view_icon.c_str(),
+                  gtk_icon_theme_has_icon(theme, app.dbg_pane_view_icon.c_str()) ? "ok" : "MISSING");
+    }
     std::printf("[udpscope]   panes: trigger=%s signals=%s body_visible=%d summary='%s'\n",
                 app.dbg_trigger_locked ? "locked" : "config",
                 app.dbg_signals_locked ? "locked" : "config", app.dbg_trigger_body_visible,

src/ui/signals-panel.ui

@@ -37,7 +37,7 @@
         </child>
         <child>
           <object class="GtkButton" id="signals_edit">
-            <property name="icon-name">emblem-system-symbolic</property>
+            <property name="icon-name">document-edit-symbolic</property>
             <property name="valign">center</property>
             <property name="css-classes">flat</property>
           </object>

src/ui_app.hpp

@@ -269,7 +269,12 @@ struct App {
   /// session: a lock is a mode, not a setting, so it is not persisted.
   bool trigger_locked = false;
   bool signals_locked = false;
+  /// The locked trigger pane's content: a small definition list, because one line cannot hold the
+  /// signal, the condition, the level and the mode, and those are what a user reads the pane for.
   GtkWidget* trigger_summary = nullptr;
+  static constexpr int kTriggerSummaryRows = 8;
+  GtkWidget* trigger_summary_keys[kTriggerSummaryRows] = {};
+  GtkWidget* trigger_summary_values[kTriggerSummaryRows] = {};
   GtkWidget* trigger_edit = nullptr;
   GtkWidget* signals_edit = nullptr;
   int dbg_trigger_locked = -1;
@@ -278,6 +283,10 @@ struct App {
   /// The compact line the locked trigger pane shows. It is the pane's whole content in that mode, so it
   /// is read rather than assumed: empty here is a locked pane showing nothing at all.
   std::string dbg_trigger_summary;
+  /// The two [edit] buttons' icons, read in each mode by clicking into it and back: a button whose icon
+  /// does not resolve is *blank*, and that is how the missing "done" icon was found.
+  std::string dbg_pane_edit_icon;
+  std::string dbg_pane_view_icon;
   /// The cursors pane: listing what the instruments read -- T0/T1/dT always, per row an Y1/Y2/dY
   /// where rulers are up, and in `mix` mode the value each cursor crosses each trace at.
   GtkWidget* cursors_mode_drop = nullptr;

src/ui_probe.cpp

@@ -2322,13 +2322,24 @@ gboolean exit_probe_step1(gpointer user) {
   App* a = static_cast<App*>(user);
   // Record the panel states before the toggles are exercised.
   a->dbg_trigger_sensitive_default = gtk_widget_get_sensitive(a->trigger_body) ? 1 : 0;
+  // The two [edit] buttons, in each mode: the icon is the only thing that says which mode the pane is
+  // in, and an icon the theme does not have draws nothing at all.
+  const auto pane_icon = [](GtkWidget* b) {
+    const char* n = b != nullptr && GTK_IS_BUTTON(b) ? gtk_button_get_icon_name(GTK_BUTTON(b)) : nullptr;
+    return std::string(n != nullptr ? n : "-");
+  };
+  a->dbg_pane_edit_icon = pane_icon(a->trigger_edit);
+  if (a->trigger_edit != nullptr) {
+    g_signal_emit_by_name(a->trigger_edit, "clicked");  // into configuration mode
+    a->dbg_pane_view_icon = pane_icon(a->trigger_edit);
+    g_signal_emit_by_name(a->trigger_edit, "clicked");  // and back to the view
+  }
   a->dbg_trigger_locked = a->trigger_locked ? 1 : 0;
   a->dbg_signals_locked = a->signals_locked ? 1 : 0;
   a->dbg_trigger_body_visible =
       a->trigger_body != nullptr && gtk_widget_get_visible(a->trigger_body) ? 1 : 0;
-  if (a->trigger_summary != nullptr) {
-    a->dbg_trigger_summary = gtk_label_get_text(GTK_LABEL(a->trigger_summary));
-  }
+  // The summary's text comes from the sync that wrote it: the container is a grid of key/value rows,
+  // and asking it for a label's text was itself a critical.
   a->dbg_panel_switch_live =
       a->trigger_switch != nullptr && gtk_widget_get_sensitive(a->trigger_switch) &&
               a->cursors_switch != nullptr && gtk_widget_get_sensitive(a->cursors_switch)

src/ui_trigger.cpp

@@ -152,6 +152,27 @@ void write_trigger_widgets(App& app) {
 /// rebuilt when a session loads.
 void sync_trigger_summary(App& app) {
   if (app.trigger_summary == nullptr) return;
+  int row = 0;
+  std::string reading;  // the same content as one line, for the dump
+  const auto put = [&](const char* key, const std::string& value) {
+    if (row >= App::kTriggerSummaryRows) return;
+    gtk_label_set_text(GTK_LABEL(app.trigger_summary_keys[row]), key);
+    gtk_label_set_text(GTK_LABEL(app.trigger_summary_values[row]), value.c_str());
+    gtk_widget_set_visible(app.trigger_summary_keys[row], TRUE);
+    gtk_widget_set_visible(app.trigger_summary_values[row], TRUE);
+    reading += std::string(reading.empty() ? "" : " | ") + key + ": " + value;
+    ++row;
+  };
+  const auto ms = [](double seconds) {
+    char b[64];
+    std::snprintf(b, sizeof(b), "%.6g ms", seconds * 1000.0);
+    return std::string(b);
+  };
+  const auto number = [](double v) {
+    char b[64];
+    std::snprintf(b, sizeof(b), "%.6g", v);
+    return std::string(b);
+  };
   TriggerConfig tc;
   std::string channel;
   {
@@ -162,42 +183,52 @@ void sync_trigger_summary(App& app) {
       channel = channels[static_cast<std::size_t>(tc.channel)].name;
     }
   }
-  char buf[192];
-  std::string text = trigger_type_text(tc.condition.type);
-  text += " · ";
-  text += channel.empty() ? "no channel" : channel;
+  put("signal", channel.empty() ? std::string("none acquired") : channel);
+  // The condition: the shape, and whatever qualifies it. A pulse width carries its comparison and its
+  // width, which is what the shape *is*; a window carries its two levels on the line below.
+  std::string condition = trigger_type_text(tc.condition.type);
   switch (tc.condition.type) {
-    case TriggerType::PulseWidth:
-      std::snprintf(buf, sizeof(buf), " · %s %.6g ms", width_cmp_text(tc.condition.cmp),
-                    tc.condition.width_s * 1000.0);
-      text += buf;
-      break;
+    case TriggerType::Edge:
     case TriggerType::Window:
-      std::snprintf(buf, sizeof(buf), " · %.6g…%.6g", tc.condition.level, tc.condition.level2);
-      text += buf;
+      condition += std::string(", ") + trigger_edge_text(tc.condition.edge);
+      break;
+    case TriggerType::PulseWidth:
+      condition += std::string(", ") + width_cmp_text(tc.condition.cmp) + " " + ms(tc.condition.width_s);
+      if (tc.condition.cmp == WidthCmp::Within || tc.condition.cmp == WidthCmp::Outside) {
+        condition += " .. " + ms(tc.condition.width2_s);
+      }
       break;
     case TriggerType::Dropout:
-      std::snprintf(buf, sizeof(buf), " · %.6g ms", tc.condition.timeout_s * 1000.0);
-      text += buf;
-      break;
-    case TriggerType::Edge:
-      std::snprintf(buf, sizeof(buf), " · level %.6g", tc.condition.level);
-      text += buf;
+      condition += std::string(", ") + ms(tc.condition.timeout_s);
       break;
   }
-  if (!(tc.condition.noise_band > 0.0) || tc.condition.type == TriggerType::Dropout) {
-    // A band is not offered for a dropout, so it is not quoted for one either.
-  } else {
-    std::snprintf(buf, sizeof(buf), " · band %.6g", tc.condition.noise_band);
-    text += buf;
+  put("condition", condition);
+  switch (tc.condition.type) {
+    case TriggerType::Window:
+      put("level", number(tc.condition.level) + " .. " + number(tc.condition.level2));
+      break;
+    case TriggerType::Dropout:
+      put("timeout", ms(tc.condition.timeout_s));
+      break;
+    default:
+      put("level", number(tc.condition.level));
+      break;
   }
-  if (tc.condition.hf_fc > 0.0) {
-    std::snprintf(buf, sizeof(buf), " · HF %.6g Hz", tc.condition.hf_fc);
-    text += buf;
+  put("mode", trigger_mode_text(tc.mode));
+  // Everything else only when it is not at its default: a line that says "band 0" is a line that says
+  // nothing, and the four lines above are the ones a user reads.
+  if (tc.condition.noise_band > 0.0 && tc.condition.type != TriggerType::Dropout) {
+    put("noise band", number(tc.condition.noise_band));
   }
-  std::snprintf(buf, sizeof(buf), " · %.6g %% pre", tc.pretrigger_pct);
-  text += buf;
-  gtk_label_set_text(GTK_LABEL(app.trigger_summary), text.c_str());
+  if (tc.condition.hf_fc > 0.0) put("HF reject", number(tc.condition.hf_fc) + " Hz");
+  if (std::fabs(tc.pretrigger_pct - 50.0) > 1.0e-9) put("pre-trigger", number(tc.pretrigger_pct) + " %");
+  if (std::fabs(tc.holdoff_s - 0.010) > 1.0e-12) put("hold-off", ms(tc.holdoff_s));
+  for (int i = row; i < App::kTriggerSummaryRows; ++i) {
+    gtk_widget_set_visible(app.trigger_summary_keys[i], FALSE);
+    gtk_widget_set_visible(app.trigger_summary_values[i], FALSE);
+  }
+  app.dbg_trigger_summary = reading;
+  gtk_widget_set_visible(app.trigger_summary, app.trigger_locked);
 }
 
 TriggerType trigger_type_at(guint i) {
@@ -616,7 +647,7 @@ GtkWidget* build_trigger_panel(App& app) {
   gtk_widget_set_hexpand(app.trigger_summary, TRUE);
   gtk_widget_set_visible(app.trigger_summary, FALSE);
   gtk_box_append(GTK_BOX(head), app.trigger_summary);
-  app.trigger_edit = gtk_button_new_from_icon_name("emblem-system-symbolic");
+  app.trigger_edit = gtk_button_new_from_icon_name("document-edit-symbolic");
   gtk_widget_add_css_class(app.trigger_edit, "flat");
   gtk_widget_set_valign(app.trigger_edit, GTK_ALIGN_CENTER);
   gtk_widget_set_tooltip_text(app.trigger_edit, "configure the trigger");
@@ -629,8 +660,30 @@ GtkWidget* build_trigger_panel(App& app) {
   g_signal_connect(app.trigger_switch, "notify::active", G_CALLBACK(on_panel_switch_toggled), &app);
   gtk_box_append(GTK_BOX(head), app.trigger_switch);
 
+  // The locked pane's content: the settings as a definition list, so the answer to "what is this set to"
+  // is four short lines rather than a row of controls.
+  app.trigger_summary = gtk_grid_new();
+  gtk_grid_set_row_spacing(GTK_GRID(app.trigger_summary), 2);
+  gtk_grid_set_column_spacing(GTK_GRID(app.trigger_summary), 12);
+  gtk_widget_set_margin_top(app.trigger_summary, 6);
+  gtk_widget_set_margin_bottom(app.trigger_summary, 6);
+  gtk_widget_set_margin_start(app.trigger_summary, 8);
+  gtk_widget_set_margin_end(app.trigger_summary, 8);
+  for (int i = 0; i < App::kTriggerSummaryRows; ++i) {
+    app.trigger_summary_keys[i] = gtk_label_new("");
+    gtk_widget_add_css_class(app.trigger_summary_keys[i], "dim-label");
+    gtk_widget_set_halign(app.trigger_summary_keys[i], GTK_ALIGN_START);
+    app.trigger_summary_values[i] = gtk_label_new("");
+    gtk_widget_set_halign(app.trigger_summary_values[i], GTK_ALIGN_START);
+    gtk_label_set_ellipsize(GTK_LABEL(app.trigger_summary_values[i]), PANGO_ELLIPSIZE_END);
+    gtk_grid_attach(GTK_GRID(app.trigger_summary), app.trigger_summary_keys[i], 0, i, 1, 1);
+    gtk_grid_attach(GTK_GRID(app.trigger_summary), app.trigger_summary_values[i], 1, i, 1, 1);
+  }
+  gtk_widget_set_visible(app.trigger_summary, FALSE);
+
   GtkWidget* outer = gtk_box_new(GTK_ORIENTATION_VERTICAL, 0);
   gtk_box_append(GTK_BOX(outer), head);
+  gtk_box_append(GTK_BOX(outer), app.trigger_summary);
   gtk_box_append(GTK_BOX(outer), box);
   return outer;
 }