5 files changed, 28 insertions, 6 deletions
diff --git a/core/core_bind.cpp b/core/core_bind.cpp
index 9a58528bd7..8ec934db62 100644
--- a/core/core_bind.cpp
+++ b/core/core_bind.cpp
@@ -196,6 +196,10 @@ int _OS::get_low_processor_usage_mode_sleep_usec() const {
 	return OS::get_singleton()->get_low_processor_usage_mode_sleep_usec();
 }
 
+void _OS::alert(const String &p_alert, const String &p_title) {
+	OS::get_singleton()->alert(p_alert, p_title);
+}
+
 String _OS::get_executable_path() const {
 	return OS::get_singleton()->get_executable_path();
 }
@@ -487,6 +491,8 @@ void _OS::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("open_midi_inputs"), &_OS::open_midi_inputs);
 	ClassDB::bind_method(D_METHOD("close_midi_inputs"), &_OS::close_midi_inputs);
 
+	ClassDB::bind_method(D_METHOD("alert", "text", "title"), &_OS::alert, DEFVAL("Alert!"));
+
 	ClassDB::bind_method(D_METHOD("set_low_processor_usage_mode", "enable"), &_OS::set_low_processor_usage_mode);
 	ClassDB::bind_method(D_METHOD("is_in_low_processor_usage_mode"), &_OS::is_in_low_processor_usage_mode);
 
diff --git a/core/core_bind.h b/core/core_bind.h
index 673dbe32c4..43f74dc9bd 100644
--- a/core/core_bind.h
+++ b/core/core_bind.h
@@ -162,6 +162,8 @@ public:
 	void set_low_processor_usage_mode_sleep_usec(int p_usec);
 	int get_low_processor_usage_mode_sleep_usec() const;
 
+	void alert(const String &p_alert, const String &p_title = "ALERT!");
+
 	String get_executable_path() const;
 	int execute(const String &p_path, const Vector<String> &p_arguments, Array r_output = Array(), bool p_read_stderr = false);
 	int create_process(const String &p_path, const Vector<String> &p_arguments);
diff --git a/core/object/undo_redo.cpp b/core/object/undo_redo.cpp
index 0532b2ae40..6808d7602d 100644
--- a/core/object/undo_redo.cpp
+++ b/core/object/undo_redo.cpp
@@ -41,9 +41,13 @@ void UndoRedo::_discard_redo() {
 	for (int i = current_action + 1; i < actions.size(); i++) {
 		for (List<Operation>::Element *E = actions.write[i].do_ops.front(); E; E = E->next()) {
 			if (E->get().type == Operation::TYPE_REFERENCE) {
-				Object *obj = ObjectDB::get_instance(E->get().object);
-				if (obj) {
-					memdelete(obj);
+				if (E->get().ref.is_valid()) {
+					E->get().ref.unref();
+				} else {
+					Object *obj = ObjectDB::get_instance(E->get().object);
+					if (obj) {
+						memdelete(obj);
+					}
 				}
 			}
 		}
@@ -242,9 +246,13 @@ void UndoRedo::_pop_history_tail() {
 
 	for (List<Operation>::Element *E = actions.write[0].undo_ops.front(); E; E = E->next()) {
 		if (E->get().type == Operation::TYPE_REFERENCE) {
-			Object *obj = ObjectDB::get_instance(E->get().object);
-			if (obj) {
-				memdelete(obj);
+			if (E->get().ref.is_valid()) {
+				E->get().ref.unref();
+			} else {
+				Object *obj = ObjectDB::get_instance(E->get().object);
+				if (obj) {
+					memdelete(obj);
+				}
 			}
 		}
 	}
diff --git a/core/os/os.cpp b/core/os/os.cpp
index 535eee4797..f7af74da3e 100644
--- a/core/os/os.cpp
+++ b/core/os/os.cpp
@@ -110,6 +110,10 @@ void OS::printerr(const char *p_format, ...) {
 	va_end(argp);
 }
 
+void OS::alert(const String &p_alert, const String &p_title) {
+	fprintf(stderr, "%s: %s\n", p_title.utf8().get_data(), p_alert.utf8().get_data());
+}
+
 void OS::set_low_processor_usage_mode(bool p_enabled) {
 	low_processor_usage_mode = p_enabled;
 }
diff --git a/core/os/os.h b/core/os/os.h
index 301718a8b3..fcb195afe1 100644
--- a/core/os/os.h
+++ b/core/os/os.h
@@ -120,6 +120,8 @@ public:
 	virtual void open_midi_inputs();
 	virtual void close_midi_inputs();
 
+	virtual void alert(const String &p_alert, const String &p_title = "ALERT!");
+
 	virtual Error open_dynamic_library(const String p_path, void *&p_library_handle, bool p_also_set_library_path = false) { return ERR_UNAVAILABLE; }
 	virtual Error close_dynamic_library(void *p_library_handle) { return ERR_UNAVAILABLE; }
 	virtual Error get_dynamic_library_symbol_handle(void *p_library_handle, const String p_name, void *&p_symbol_handle, bool p_optional = false) { return ERR_UNAVAILABLE; }