add on attach for emit signal

bin/main.cpp

@@ -1,6 +1,7 @@
 #include "layers/test_panel/test_panel.hpp"
 #include "layers/test_panel_2/test_panel_2.hpp"
 #include "layers/opengl_panel/opengl_panel.hpp"
+#include "layers/local_panel/local_panel.hpp"
 
 namespace sandbox
 {
@@ -9,13 +10,6 @@ namespace sandbox
     public:
       test_app(std::string app_name) : VE::application{ app_name } {};
       ~test_app() = default;
-
-    public:
-      template<typename... Args>
-      void push_layer(Args... args) 
-      { 
-        this->VE::application::push_layer(args...); 
-      }
   };
 }
 
@@ -31,6 +25,13 @@ namespace VE
       new sandbox::opengl_panel{}
     );
 
+    app.on_attach(
+      new sandbox::test_panel{},
+      new sandbox::test_panel_2{},
+      new sandbox::opengl_panel{},
+      new sandbox::local_panel{}
+    );
+
     return app;
   }
 }