add protection to avoid exception

diff --git a/src/GLViewer/GLViewer_Viewer2d.cxx b/src/GLViewer/GLViewer_Viewer2d.cxx
index 74114b3f4af47633863b190edd7bc05d95f7b2e0..c7a1d297de24ed0903c18b0388a57f1a1696b5cc 100644 (file)
--- a/src/GLViewer/GLViewer_Viewer2d.cxx
+++ b/src/GLViewer/GLViewer_Viewer2d.cxx
@@ -230,6 +230,8 @@ void GLViewer_Viewer2d::activateDrawers( QValueList<GLViewer_Object*>& theObject
                 aDrawer = (*oit)->getDrawer();
             }
         }
+        if ( !aDrawer )
+          continue;
         aDrawer->addObject( (*oit) );
 
         int aPriority = aDrawer->getPriority();