Added an easy API to yield to a specific time by doing:

yield( get_tree().create_timer(5.0), "timeout" )

scene/main/scene_main_loop.cpp

@@ -45,6 +45,30 @@
 #include "scene/resources/material.h"
 #include "scene/resources/mesh.h"
 
+
+void SceneTreeTimer::_bind_methods() {
+
+	ObjectTypeDB::bind_method(_MD("set_time_left","time"),&SceneTreeTimer::set_time_left);
+	ObjectTypeDB::bind_method(_MD("get_time_left"),&SceneTreeTimer::get_time_left);
+
+	ADD_SIGNAL(MethodInfo("timeout"));
+}
+
+
+void SceneTreeTimer::set_time_left(float p_time) {
+	time_left=p_time;
+}
+
+float SceneTreeTimer::get_time_left() const {
+	return time_left;
+}
+
+
+SceneTreeTimer::SceneTreeTimer() {
+	time_left=0;
+}
+
+
 void SceneTree::tree_changed() {
 
 	tree_version++;
@@ -547,6 +571,23 @@ bool SceneTree::idle(float p_time){
 
 	_flush_delete_queue();
 
+	//go through timers
+
+	for (List<Ref<SceneTreeTimer> >::Element *E=timers.front();E;) {
+
+		List<Ref<SceneTreeTimer> >::Element *N = E->next();
+
+		float time_left = E->get()->get_time_left();
+		time_left-=p_time;
+		E->get()->set_time_left(time_left);
+
+		if (time_left<0) {
+			E->get()->emit_signal("timeout");
+			timers.erase(E);
+		}
+		E=N;
+	}
+
 	return _quit;
 }
 
@@ -1604,6 +1645,16 @@ void SceneTree::drop_files(const Vector<String>& p_files,int p_from_screen) {
 	MainLoop::drop_files(p_files,p_from_screen);
 }
 
+
+Ref<SceneTreeTimer> SceneTree::create_timer(float p_delay_sec) {
+
+	Ref<SceneTreeTimer> stt;
+	stt.instance();
+	stt->set_time_left(p_delay_sec);
+	timers.push_back(stt);
+	return stt;
+}
+
 void SceneTree::_bind_methods() {
 
 
@@ -1634,6 +1685,8 @@ void SceneTree::_bind_methods() {
 	ObjectTypeDB::bind_method(_MD("is_paused"),&SceneTree::is_paused);
 	ObjectTypeDB::bind_method(_MD("set_input_as_handled"),&SceneTree::set_input_as_handled);
 
+	ObjectTypeDB::bind_method(_MD("create_timer:SceneTreeTimer","time_sec"),&SceneTree::create_timer);
+
 
 	ObjectTypeDB::bind_method(_MD("get_node_count"),&SceneTree::get_node_count);
 	ObjectTypeDB::bind_method(_MD("get_frame"),&SceneTree::get_frame);

scene/main/scene_main_loop.h

@@ -47,6 +47,22 @@ class Viewport;
 class Material;
 class Mesh;
 
+
+
+class SceneTreeTimer : public Reference {
+	OBJ_TYPE(SceneTreeTimer,Reference);
+
+	float time_left;
+protected:
+	static void _bind_methods();
+public:
+
+	void set_time_left(float p_time);
+	float get_time_left() const;
+
+	SceneTreeTimer();
+};
+
 class SceneTree : public MainLoop {
 
 	_THREAD_SAFE_CLASS_
@@ -155,6 +171,8 @@ private:
 	void _change_scene(Node* p_to);
 	//void _call_group(uint32_t p_call_flags,const StringName& p_group,const StringName& p_function,const Variant& p_arg1,const Variant& p_arg2);
 
+	List<Ref<SceneTreeTimer> > timers;
+
 	static SceneTree *singleton;
 friend class Node;
 
@@ -339,6 +357,8 @@ public:
 	Error change_scene_to(const Ref<PackedScene>& p_scene);
 	Error reload_current_scene();
 
+	Ref<SceneTreeTimer> create_timer(float p_delay_sec);
+
 	//used by Main::start, don't use otherwise
 	void add_current_scene(Node * p_current);
 

scene/register_scene_types.cpp

@@ -632,6 +632,7 @@ void register_scene_types() {
 	ObjectTypeDB::register_type<PackedScene>();
 
 	ObjectTypeDB::register_type<SceneTree>();
+	ObjectTypeDB::register_virtual_type<SceneTreeTimer>(); //sorry, you can't create it
 
 	OS::get_singleton()->yield(); //may take time to init