diff --git a/lib/event_manager.gd b/lib/event_manager.gd
index 276a2f48..c482ec3e 100644
--- a/lib/event_manager.gd
+++ b/lib/event_manager.gd
@@ -2,11 +2,25 @@ extends Node
 
 var ol: OverlayWindow
 
+var _queue: Array[Alert] = []
 
 # Called when the node enters the scene tree for the first time.
 func _ready() -> void:
-	ol = get_tree().root.get_node("MainWin")
+	if get_tree().root.has_node("MainWin"):
+		ol = get_tree().root.get_node("MainWin")
 
+func add_alert(alert: Alert) -> void:
+	if get_children().any(func(x): return x is Alert):
+		_queue.append(alert)
+	else:
+		add_child(alert)
+
+func _process(_d: float) -> void:
+	if _queue.is_empty(): return
+	if get_children().any(func(x): return x is Alert):
+		return
+	var alert: Alert = _queue.pop_front()
+	add_child(alert)
 
 func test_notification(msg: String) -> void:
 	var lbl = Label.new()