diff --git a/xSDL/xApplication.cpp b/xSDL/xApplication.cpp
index 9e9d862..260ce2a 100644
--- a/xSDL/xApplication.cpp
+++ b/xSDL/xApplication.cpp
@@ -244,33 +244,17 @@ bool xApplication::setImage(const char *url){
 
 
 
-/** adds new sprite to draw (with its identifier) */
-void xApplication::push(string id, xElement* sprite){
+/** adds new sprite to draw */
+void xApplication::push(xElement* sprite){
 	_mutex_draw.try_lock();
-	_sprites[id] = sprite;
+	_sprites.insert(sprite);
 	_mutex_draw.unlock();
 }
 
-/** removes a sprite to draw (from its identifier) */
-void xApplication::pull(string id){
-	_mutex_draw.try_lock();
-	_sprites.erase(id);
-	_mutex_draw.unlock();
-}
-
-
 /** removes a sprite to draw (from its address) */
 void xApplication::pull(xElement* sprite){
 	_mutex_draw.try_lock();
-
-	map<string, xElement*>::iterator it;
-	for( it = _sprites.begin() ; it != _sprites.end() ; it++ ){
-		if( sprite == it->second ){
-			_sprites.erase(it);
-			break;
-		}
-	}
-
+	_sprites.erase(sprite);
 	_mutex_draw.unlock();
 }
 
@@ -297,9 +281,9 @@ void xApplication::render(){
 
 
 	/* 4. draw every sprite */
-	map<string, xElement*>::iterator it = _sprites.begin();
-	for( ; it != _sprites.end() ; it++ ){
-		xElement* sprite = it->second;
+	set<xElement*>::iterator it;
+	for( it = _sprites.begin() ; it != _sprites.end() ; it++ ){
+		xElement* sprite = *it;
 		sprite->draw(_renderer);
 	}
 
diff --git a/xSDL/xApplication.h b/xSDL/xApplication.h
index beaf794..2070623 100644
--- a/xSDL/xApplication.h
+++ b/xSDL/xApplication.h
@@ -42,8 +42,7 @@
 			// bool hit(string current, int movex=0, int movey=0);  // Gestion des collisions
 
 			/** scene */
-			void push(string id, xElement* sprite);
-			void pull(string id);
+			void push(xElement* sprite);
 			void pull(xElement *sprite);
 			void clear();
 
@@ -68,6 +67,9 @@
 			// event management
 			xController _controller;
 
+			// sprites
+			set<xElement*> _sprites;
+
 			// sdl objects
 			SDL_Window   *_window;
 			SDL_Rect      _winrect;
@@ -75,12 +77,6 @@
 			SDL_Renderer *_renderer;
 			SDL_Texture  *_texture;
 
-			// sprites
-			map<string, xElement*> _sprites;
-
-			// shared threads
-			map<string, thread*> _pool;
-
 			// thread safety
 			mutex _mutex_draw;
 	};