fix(tray): hide module when no items are visible

Tray::update() already had logic to hide the module when all child items were passive, but it was only re-run on item add/remove — never on a status change. When the last visible item transitioned to Passive, the item hid itself but the now-empty module remained visible.

Connect Tray to each item's Gtk::EventBox signal_show/signal_hide so update() runs on every visibility transition, and simplify update() to check child->get_visible() directly instead of inspecting the `passive` CSS class. The Tray-level `show-passive-items` read becomes redundant since Item already honours it when deciding its own visibility; remove it along with the now-unused Tray::show_passive_ member.

Fixes: #3721

src/modules/sni/tray.cpp

@@ -23,9 +23,6 @@ Tray::Tray(const std::string& id, const Bar& bar, const Json::Value& config)
   if (config_["spacing"].isUInt()) {
     box_.set_spacing(config_["spacing"].asUInt());
   }
-  if (config["show-passive-items"].isBool()) {
-    show_passive_ = config["show-passive-items"].asBool();
-  }
   nb_hosts_ += 1;
   if (config_["icons"].isObject()) {
     IconManager::instance().setIconsConfig(config_["icons"]);
@@ -39,6 +36,8 @@ void Tray::onAdd(std::unique_ptr<Item>& item) {
   } else {
     box_.pack_start(item->event_box);
   }
+  item->event_box.signal_show().connect([this] { dp.emit(); });
+  item->event_box.signal_hide().connect([this] { dp.emit(); });
   dp.emit();
 }
 
@@ -48,17 +47,9 @@ void Tray::onRemove(std::unique_ptr<Item>& item) {
 }
 
 auto Tray::update() -> void {
-  // Show tray only when items are available
   std::vector<Gtk::Widget*> children = box_.get_children();
-  if (show_passive_) {
-    event_box_.set_visible(!children.empty());
-  } else {
-    event_box_.set_visible(!std::all_of(children.begin(), children.end(), [](Gtk::Widget* child) {
-      return child->get_style_context()->has_class("passive");
-    }));
-  }
-
-  // Call parent update
+  event_box_.set_visible(std::any_of(children.begin(), children.end(),
+                                     [](Gtk::Widget* child) { return child->get_visible(); }));
   AModule::update();
 }