only set offscreen mode when gfx module is available

git-svn-id: https://dng.biozentrum.unibas.ch/svn/openstructure/trunk@2062 5a81b35b-ba03-0410-adc8-b2c5c5119f08

scripts/init_cl.py

@@ -24,8 +24,10 @@ import os.path
 HistoryFile=os.path.expanduser('~/.ost_history')
 InGUIMode=False
 
-  
-gfx.set_offscreen_mode()
+try:  
+  gfx.set_offscreen_mode()
+except NameError:
+  pass
 sys.ps1='ost> '
 sys.ps2='..... '
 print ''