pstats: Workaround for Gtk bug that causes UI to crash when a session is closed

As workaround for https://gitlab.gnome.org/GNOME/gtk/-/merge_requests/2029, we manually create a GtkFlowBoxChild instance and attach the label to it and increase its reference count so it it not prematurely destroyed when removed from the GtkFlowBox, causing the UI to segfault.

pandatool/src/gtk-stats/gtkStatsMonitor.cxx

@@ -60,8 +60,9 @@ close() {
 
   remove_all_graphs();
 
-  for (GtkWidget *label : _status_bar_labels) {
-    gtk_container_remove(GTK_CONTAINER(_status_bar), label);
+  for (GtkWidget *flow_box_child : _status_bar_labels) {
+    gtk_container_remove(GTK_CONTAINER(_status_bar), flow_box_child);
+    g_object_unref(flow_box_child);
   }
   _status_bar_collectors.clear();
   _status_bar_labels.clear();
@@ -252,7 +253,8 @@ idle() {
     gtk_label_set_text(GTK_LABEL(_frame_rate_label), buffer);
 
     if (!_status_bar_labels.empty()) {
-      gtk_label_set_text(GTK_LABEL(_status_bar_labels[0]), buffer);
+      GtkWidget *label = gtk_bin_get_child(GTK_BIN(_status_bar_labels[0]));
+      gtk_label_set_text(GTK_LABEL(label), buffer);
     }
   }
 }
@@ -607,9 +609,16 @@ update_status_bar() {
   size_t li = 1;
   collectors.push_back(0);
   if (_status_bar_labels.empty()) {
+    // As workaround for https://gitlab.gnome.org/GNOME/gtk/-/merge_requests/2029
+    // We manually create a GtkFlowBoxChild instance and attach the label to it
+    // and increase its reference count so it it not prematurely destroyed when
+    // removed from the GtkFlowBox, causing the app to segfault.
     GtkWidget *label = gtk_label_new("");
-    gtk_container_add(GTK_CONTAINER(_status_bar), label);
-    _status_bar_labels.push_back(label);
+    GtkWidget *flow_box_child = gtk_flow_box_child_new();
+    gtk_container_add(GTK_CONTAINER(flow_box_child), label);
+    gtk_container_add(GTK_CONTAINER(_status_bar), flow_box_child);
+    _status_bar_labels.push_back(flow_box_child);
+    g_object_ref(flow_box_child);
   }
 
   // Gather the top-level collector list.
@@ -639,15 +648,21 @@ update_status_bar() {
       std::string text = def._name;
       text += ": " + PStatGraph::format_number(value, PStatGraph::GBU_named | PStatGraph::GBU_show_units, def._level_units);
 
+      GtkWidget *flow_box_child;
       GtkWidget *label;
       if (li < _status_bar_labels.size()) {
-        label = _status_bar_labels[li++];
+          flow_box_child = _status_bar_labels[li++];
+        label = gtk_bin_get_child(GTK_BIN(flow_box_child));
         gtk_label_set_text(GTK_LABEL(label), text.c_str());
       }
       else {
         label = gtk_label_new(text.c_str());
-        gtk_container_add(GTK_CONTAINER(_status_bar), label);
-        _status_bar_labels.push_back(label);
+        // See comment above
+        flow_box_child = gtk_flow_box_child_new();
+        gtk_container_add(GTK_CONTAINER(flow_box_child), label);
+        gtk_container_add(GTK_CONTAINER(_status_bar), flow_box_child);
+        _status_bar_labels.push_back(flow_box_child);
+        g_object_ref(flow_box_child);
       }
 
       collectors.push_back(collector);
@@ -737,7 +752,8 @@ status_bar_button_event(GtkWidget *widget, GdkEventButton *event, gpointer data)
 
     gtk_widget_show_all(menu);
 
-    GtkWidget *label = monitor->_status_bar_labels[index];
+    GtkWidget *flow_box_child = monitor->_status_bar_labels[index];
+    GtkWidget *label = gtk_bin_get_child(GTK_BIN(flow_box_child));
     gtk_menu_popup_at_widget(GTK_MENU(menu), label,
                              GDK_GRAVITY_NORTH_WEST,
                              GDK_GRAVITY_SOUTH_WEST, nullptr);
@@ -855,7 +871,8 @@ handle_status_bar_popup(int item) {
 
     gtk_widget_show_all(menu);
 
-    GtkWidget *label = _status_bar_labels[item];
+    GtkWidget *flow_box_child = _status_bar_labels[item];
+    GtkWidget *label = gtk_bin_get_child(GTK_BIN(flow_box_child));
     gtk_menu_popup_at_widget(GTK_MENU(menu), label,
                              GDK_GRAVITY_NORTH_WEST,
                              GDK_GRAVITY_SOUTH_WEST, nullptr);

pandatool/src/gtk-stats/gtkStatsServer.cxx

@@ -123,6 +123,7 @@ make_monitor(const NetAddress &address) {
 
   if (_status_bar_label != nullptr) {
     gtk_container_remove(GTK_CONTAINER(_status_bar), _status_bar_label);
+    g_object_unref(_status_bar_label);
     _status_bar_label = nullptr;
   }
 
@@ -177,9 +178,16 @@ new_session() {
       std::ostringstream strm;
       strm << "Waiting for client to connect on port " << _port << "...";
       std::string title = strm.str();
-      _status_bar_label = gtk_label_new(title.c_str());
+      // As workaround for https://gitlab.gnome.org/GNOME/gtk/-/merge_requests/2029
+      // We manually create a GtkFlowBoxChild instance and attach the label to it
+      // and increase its reference count so it it not prematurely destroyed when
+      // removed from the GtkFlowBox, causing the app to segfault.
+      GtkWidget * label = gtk_label_new(title.c_str());
+      _status_bar_label = gtk_flow_box_child_new();
+      gtk_container_add(GTK_CONTAINER(_status_bar_label), label);
       gtk_container_add(GTK_CONTAINER(_status_bar), _status_bar_label);
       gtk_widget_show(_status_bar_label);
+      g_object_ref(_status_bar_label);
     }
 
     gtk_widget_set_sensitive(_new_session_menu_item, FALSE);
@@ -462,6 +470,7 @@ close_session() {
 
   if (_status_bar_label != nullptr) {
     gtk_container_remove(GTK_CONTAINER(_status_bar), _status_bar_label);
+    g_object_unref(_status_bar_label);
     _status_bar_label = nullptr;
   }