Added FEATURE flag, fixed rare segfault

tetris/tetris.cpp

@@ -148,19 +148,19 @@ int main() {
             updateSize();
             g_update_size = false;
         }
-        for(size_t i = 0; i < g_update_scenes.size(); i++) {
+        while ( !g_update_scenes.empty() ) {
             g_update_scenes.back()->updateSizeAndPosition();
             g_update_scenes.pop_back();
         }
-        for(size_t i = 0; i < g_update_objects.size(); i++) {
+        while ( !g_update_objects.empty() ) {
             g_update_objects.back()->updateSizeAndPosition();
             g_update_objects.pop_back();
         }
 
-
         renderer->clearRenderer();
-        for ( auto &x : g_active_scenes ) {
-            x->renderScene( false );
+        for ( size_t i = 0; i < g_active_scenes.size(); i++ ) {
+            g_active_scenes[i]->updateScene();
+            g_active_scenes[i]->renderScene( false );
         }
         renderer->presentRenderer();
         g_wait_for_anim = false;