add 'onselect' callback & remove 'default' tag

src/graphics/ui/elements/SelectBox.cpp

@@ -26,8 +26,9 @@ SelectBox::SelectBox(
             auto button = std::make_shared<Button>(
                 gui, option.text, glm::vec4(10.0f), nullptr, glm::vec2(-1.0f)
             );
-            button->listenFocus([this, option](GUI&) {
+            button->listenFocus([this, option](GUI& gui) {
                 setSelected(option);
+                changeCallbacks.notify(gui, option.value);
             });
             panel->add(button);
         }
@@ -40,6 +41,10 @@ SelectBox::SelectBox(
     });
 }
 
+void SelectBox::listenChange(onstringchange&& callback) {
+    changeCallbacks.listen(std::move(callback));
+}
+
 void SelectBox::setSelected(const Option& selected) {
     this->selected = selected;
     this->label->setText(selected.text);

src/graphics/ui/elements/SelectBox.hpp

@@ -14,6 +14,7 @@ namespace gui {
     private:
         std::vector<Option> options;
         Option selected {};
+        StringCallbacksSet changeCallbacks;
     public:
         SelectBox(
             GUI& gui,
@@ -23,6 +24,8 @@ namespace gui {
             const glm::vec4& padding
         );
 
+        void listenChange(onstringchange&& callback);
+
         void setSelected(const Option& selected);
 
         const Option& getSelected() const;

src/graphics/ui/elements/UINode.hpp

@@ -21,25 +21,33 @@ namespace gui {
 
     using onaction = std::function<void(GUI&)>;
     using onnumberchange = std::function<void(GUI&, double)>;
+    using onstringchange = std::function<void(GUI&, const std::string&)>;
 
-    class ActionsSet {
-        std::unique_ptr<std::vector<onaction>> callbacks;
+    template<typename... Args>
+    class CallbacksSet {
     public:
-        void listen(const onaction& callback) {
+        using Func = std::function<void(Args...)>;
+    private:
+        std::unique_ptr<std::vector<Func>> callbacks;
+    public:
+        void listen(const Func& callback) {
             if (callbacks == nullptr) {
-                callbacks = std::make_unique<std::vector<onaction>>();
+                callbacks = std::make_unique<std::vector<Func>>();
             }
             callbacks->push_back(callback);
         }
 
-        void notify(GUI& gui) {
+        void notify(Args&&... args) {
             if (callbacks) {
                 for (auto& callback : *callbacks) {
-                    callback(gui);
+                    callback(std::forward<Args>(args)...);
                 }
             }
         }
     };
+
+    using ActionsSet = CallbacksSet<GUI&>;
+    using StringCallbacksSet = CallbacksSet<GUI&, const std::string&>;
     
     enum class Align {
         left, center, right,