Add a message when there is nothing to Undo or Redo

core/undo_redo.cpp

@@ -299,26 +299,30 @@ void UndoRedo::_process_operation_list(List<Operation>::Element *E) {
 	}
 }
 
-void UndoRedo::redo() {
+bool UndoRedo::redo() {
 
-	ERR_FAIL_COND(action_level > 0);
+	ERR_FAIL_COND_V(action_level > 0, false);
 
 	if ((current_action + 1) >= actions.size())
-		return; //nothing to redo
+		return false; //nothing to redo
 	current_action++;
 
 	_process_operation_list(actions[current_action].do_ops.front());
 	version++;
+
+	return true;
 }
 
-void UndoRedo::undo() {
+bool UndoRedo::undo() {
 
-	ERR_FAIL_COND(action_level > 0);
+	ERR_FAIL_COND_V(action_level > 0, false);
 	if (current_action < 0)
-		return; //nothing to redo
+		return false; //nothing to redo
 	_process_operation_list(actions[current_action].undo_ops.front());
 	current_action--;
 	version--;
+
+	return true;
 }
 
 void UndoRedo::clear_history() {

core/undo_redo.h

@@ -109,8 +109,8 @@ public:
 
 	void commit_action();
 
-	void redo();
-	void undo();
+	bool redo();
+	bool undo();
 	String get_current_action_name() const;
 	void clear_history();
 

editor/editor_node.h

@@ -680,6 +680,7 @@ public:
 
 	Ref<Theme> get_editor_theme() const { return theme; }
 
+	void show_accept(const String &p_text, const String &p_title);
 	void show_warning(const String &p_text, const String &p_title = "Warning!");
 
 	Error export_preset(const String &p_preset, const String &p_path, bool p_debug, const String &p_password, bool p_quit_after = false);