Ge curve bugfix for datafile not found

xtt/lib/ge/gtk/ge_curve_gtk.cpp

 /* 
  * Proview   Open Source Process Control.
- * Copyright (C) 2005-2011 SSAB Oxelosund AB.
+ * Copyright (C) 2005-2012 SSAB EMEA AB.
  *
  * This file is part of Proview.
  *
@@ -636,6 +636,9 @@ GeCurveGtk::GeCurveGtk( void *gc_parent_ctx,
   const int    	nav_height = 120;
   pwr_tFileName fname;
 
+  if ( !cd)
+    return;
+
   cdh_StrncpyCutOff( title, curve_name, sizeof(title), 1);
 
   // Gtk