diff --git a/src/common/interfaces.h b/src/common/interfaces.h
index e4f55c8e6..7562807fb 100644
--- a/src/common/interfaces.h
+++ b/src/common/interfaces.h
@@ -477,8 +477,8 @@ public:
   virtual QString decorationInfo(QAction *a) const {return decorationInfo(ID(a));}
 
 
-  virtual bool startDecorate(QAction * /*mode*/, MeshDocument &/*m*/, RichParameterSet * /*param*/, GLArea * /*parent*/) {}
-  virtual bool startDecorate(QAction * /*mode*/, MeshModel &/*m*/, RichParameterSet * /*param*/, GLArea * /*parent*/) {}
+  virtual bool startDecorate(QAction * /*mode*/, MeshDocument &/*m*/, RichParameterSet * /*param*/, GLArea * /*parent*/) {return false;}
+  virtual bool startDecorate(QAction * /*mode*/, MeshModel &/*m*/, RichParameterSet * /*param*/, GLArea * /*parent*/) {return false;}
   virtual void decorateMesh(QAction * /*mode*/,  MeshModel &/*m*/, RichParameterSet *, GLArea * /*parent*/, QPainter */*p*/, GLLogStream &/*log*/) = 0;
   virtual void decorateDoc(QAction * /*mode*/,  MeshDocument &/*m*/, RichParameterSet *, GLArea * /*parent*/, QPainter */*p*/, GLLogStream &/*log*/) = 0;
   virtual void endDecorate(QAction * /*mode*/,   MeshModel &/*m*/, RichParameterSet *, GLArea * /*parent*/){}