EBO implementation + resize + keyboard

include/uui/application.hpp

@@ -12,5 +12,8 @@ class Application
 public:
 	virtual void run() = 0;
 	virtual std::weak_ptr<Window> add_window(int width, int height, const std::string& title) = 0;
+
+protected:
+	static bool application_created;
 };
 } // namespace uui

include/uui/opengl/box.hpp

@@ -16,6 +16,7 @@ public:
 private:
 	GLuint gl_vbo;
 	GLuint gl_vao;
+	GLuint gl_ebo;
 	GLuint gl_program;
 };