Description of Problem: 
Sometimes scroll_to_cell doesn't scroll where I tell it to. 
 
Version-Release number of selected component (if applicable): 
gtk2-2.0.6-8 
pygtk2-1.99.12-7 
 
How Reproducible: 
100% 
 
Steps to Reproduce: 
See attached testcase 
1. python gtk2bug.py 
2. Click 'Forward' 
3. Inspect treeview 
 
Actual Results: 
Scrolled to near the beginning. 
 
Expected Results: 
Scrolled to keep item 150 centred. 
 
Additional Information: 
Recompiling gtk2 without -O2 makes the problem go away, as does inserting 
  while gtk.events_pending (): 
    gtk.mainiteration () 
in the callback function.