From ef11efce55380da1e23c6c511c9794099b99181c Mon Sep 17 00:00:00 2001
From: wmayer <wmayer@users.sourceforge.net>
Date: Wed, 4 Oct 2017 20:03:59 +0200
Subject: [PATCH] check for null string

---
 src/Base/ParameterPy.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/Base/ParameterPy.cpp b/src/Base/ParameterPy.cpp
index 4aaa65d8ee..7ce79e3e2a 100644
--- a/src/Base/ParameterPy.cpp
+++ b/src/Base/ParameterPy.cpp
@@ -69,6 +69,8 @@ public:
     }
     virtual void OnChange(ParameterGrp::SubjectType &rCaller,ParameterGrp::MessageType Reason)
     {
+        if (!Reason || Reason[0] == '\0')
+            return;
         Base::PyGILStateLocker lock;
         try {
             ParameterGrp& rGrp = static_cast<ParameterGrp&>(rCaller);