Fixed EventSystem warnings being spammed when loading a scene additively

Author: yasirkula

Plugins/SimpleFileBrowser/Scripts/EventSystemHandler.cs

@@ -33,6 +33,9 @@ private void OnDisable()
 
 		private void OnSceneLoaded( Scene scene, LoadSceneMode mode )
 		{
+#if UNITY_2017_2_OR_NEWER
+			DeactivateEventSystem();
+#endif
 			ActivateEventSystemIfNeeded();
 		}