Implement proper radio group handling for GTK menus

Added thread-safe static mapping of radio group IDs to GTK radio menu item groups. The new ApplyRadioGroup method ensures radio menu items are correctly grouped in GTK when SetRadioGroup is called.

Author: lijy91

src/platform/linux/menu_linux.cpp

@@ -6,6 +6,8 @@
 #include <optional>
 #include <string>
 #include <vector>
+#include <unordered_map>
+#include <mutex>
 #include "../../foundation/id_allocator.h"
 #include "../../image.h"
 #include "../../menu.h"
@@ -22,6 +24,25 @@ static void OnGtkMenuItemActivate(GtkMenuItem* /*item*/, gpointer user_data) {
   menu_item->Emit(MenuItemClickedEvent(menu_item->GetId()));
 }
 
+// For checkbox and radio items we listen to "toggled" to avoid recursive
+// activate emissions when GTK internally updates group state. For radio items,
+// we only emit when the item becomes active.
+static void OnGtkCheckMenuItemToggled(GtkCheckMenuItem* item, gpointer user_data) {
+  MenuItem* menu_item = static_cast<MenuItem*>(user_data);
+  if (!menu_item) {
+    return;
+  }
+  gboolean active = gtk_check_menu_item_get_active(item);
+  if (menu_item->GetType() == MenuItemType::Radio) {
+    if (active) {
+      menu_item->Emit(MenuItemClickedEvent(menu_item->GetId()));
+    }
+  } else {
+    // Checkbox: emit on any toggle
+    menu_item->Emit(MenuItemClickedEvent(menu_item->GetId()));
+  }
+}
+
 static void OnGtkMenuShow(GtkWidget* /*menu*/, gpointer user_data) {
   Menu* menu_obj = static_cast<Menu*>(user_data);
   if (!menu_obj) {
@@ -69,6 +90,29 @@ class MenuItem::Impl {
         radio_group_(-1),
         accelerator_("", KeyboardAccelerator::None) {}
 
+  void ApplyRadioGroup() {
+    if (!gtk_menu_item_ || type_ != MenuItemType::Radio || radio_group_ < 0) {
+      return;
+    }
+
+    std::lock_guard<std::mutex> lock(s_group_map_mutex_);
+
+    GSList* target_group = nullptr;
+    auto it = s_group_map_.find(radio_group_);
+    if (it != s_group_map_.end()) {
+      target_group = it->second;
+    } else {
+      target_group = gtk_radio_menu_item_get_group(GTK_RADIO_MENU_ITEM(gtk_menu_item_));
+      s_group_map_[radio_group_] = target_group;
+    }
+
+    gtk_radio_menu_item_set_group(GTK_RADIO_MENU_ITEM(gtk_menu_item_), target_group);
+
+    // Update stored head pointer after potential re-linking
+    s_group_map_[radio_group_] =
+        gtk_radio_menu_item_get_group(GTK_RADIO_MENU_ITEM(gtk_menu_item_));
+  }
+
   MenuItemId id_;
   GtkWidget* gtk_menu_item_;
   std::optional<std::string> title_;
@@ -79,8 +123,16 @@ class MenuItem::Impl {
   int radio_group_;
   KeyboardAccelerator accelerator_;
   std::shared_ptr<Menu> submenu_;
+
+  // Shared map from logical group id to GTK group list
+  static std::unordered_map<int, GSList*> s_group_map_;
+  static std::mutex s_group_map_mutex_;
 };
 
+// Static member definitions
+std::unordered_map<int, GSList*> MenuItem::Impl::s_group_map_;
+std::mutex MenuItem::Impl::s_group_map_mutex_;
+
 MenuItem::MenuItem(const std::string& label, MenuItemType type) {
   MenuItemId id = IdAllocator::Allocate<MenuItem>();
   GtkWidget* gtk_item = nullptr;
@@ -110,9 +162,13 @@ MenuItem::MenuItem(const std::string& label, MenuItemType type) {
     pimpl_->title_.reset();
   }
 
-  // Connect activation signal for click events (except separators)
+  // Connect signals for click/toggle events (except separators)
   if (gtk_item && type != MenuItemType::Separator) {
-    g_signal_connect(G_OBJECT(gtk_item), "activate", G_CALLBACK(OnGtkMenuItemActivate), this);
+    if (type == MenuItemType::Checkbox || type == MenuItemType::Radio) {
+      g_signal_connect(G_OBJECT(gtk_item), "toggled", G_CALLBACK(OnGtkCheckMenuItemToggled), this);
+    } else {
+      g_signal_connect(G_OBJECT(gtk_item), "activate", G_CALLBACK(OnGtkMenuItemActivate), this);
+    }
   }
 }
 
@@ -129,8 +185,13 @@ MenuItem::MenuItem(void* menu_item) {
   }
 
   if (pimpl_->gtk_menu_item_) {
-    g_signal_connect(G_OBJECT(pimpl_->gtk_menu_item_), "activate",
-                     G_CALLBACK(OnGtkMenuItemActivate), this);
+    if (GTK_IS_CHECK_MENU_ITEM(pimpl_->gtk_menu_item_)) {
+      g_signal_connect(G_OBJECT(pimpl_->gtk_menu_item_), "toggled",
+                       G_CALLBACK(OnGtkCheckMenuItemToggled), this);
+    } else {
+      g_signal_connect(G_OBJECT(pimpl_->gtk_menu_item_), "activate",
+                       G_CALLBACK(OnGtkMenuItemActivate), this);
+    }
   }
 }
 
@@ -284,20 +345,20 @@ void MenuItem::SetState(MenuItemState state) {
   if (pimpl_->gtk_menu_item_) {
     if (pimpl_->type_ == MenuItemType::Checkbox) {
       gboolean active = (state == MenuItemState::Checked) ? TRUE : FALSE;
-      // Block the "activate" signal to prevent recursive triggering
+      // Block the "toggled" signal to prevent recursive triggering
       g_signal_handlers_block_by_func(G_OBJECT(pimpl_->gtk_menu_item_), 
-                                      (gpointer)OnGtkMenuItemActivate, this);
+                                      (gpointer)OnGtkCheckMenuItemToggled, this);
       gtk_check_menu_item_set_active(GTK_CHECK_MENU_ITEM(pimpl_->gtk_menu_item_), active);
       g_signal_handlers_unblock_by_func(G_OBJECT(pimpl_->gtk_menu_item_), 
-                                        (gpointer)OnGtkMenuItemActivate, this);
+                                        (gpointer)OnGtkCheckMenuItemToggled, this);
     } else if (pimpl_->type_ == MenuItemType::Radio) {
       gboolean active = (state == MenuItemState::Checked) ? TRUE : FALSE;
-      // Block the "activate" signal to prevent recursive triggering
+      // Block the "toggled" signal to prevent recursive triggering
       g_signal_handlers_block_by_func(G_OBJECT(pimpl_->gtk_menu_item_), 
-                                      (gpointer)OnGtkMenuItemActivate, this);
+                                      (gpointer)OnGtkCheckMenuItemToggled, this);
       gtk_check_menu_item_set_active(GTK_CHECK_MENU_ITEM(pimpl_->gtk_menu_item_), active);
       g_signal_handlers_unblock_by_func(G_OBJECT(pimpl_->gtk_menu_item_), 
-                                        (gpointer)OnGtkMenuItemActivate, this);
+                                        (gpointer)OnGtkCheckMenuItemToggled, this);
     }
   }
 }
@@ -314,7 +375,7 @@ MenuItemState MenuItem::GetState() const {
 
 void MenuItem::SetRadioGroup(int group_id) {
   pimpl_->radio_group_ = group_id;
-  // TODO: Implement proper radio grouping for GTK
+  pimpl_->ApplyRadioGroup();
 }
 
 int MenuItem::GetRadioGroup() const {