Created attachment 579692 [details]
first screencast of the issue (list jumps back)

Description of problem:

The first attached screencast shows how scrolling with the down-arrow-button on the bottom of the list doesn't work. Whenever I scroll with it under the currently seen area and leave the arrow button, list jumps back to the original position.

The second screencast shows how using scroll-wheel doesn't work either. The list just doesn't scroll.

The only way how to get to the bottom of the list is with keyboard.

Version-Release number of selected component (if applicable):
gtk2-2.24.10-1.x86_64
gtk3-3.3.20-1.x86_64
gnome-shell-3.4.0-2.x86_64
pygtk2-2.24.0-1.1.x86_64

How reproducible:
100%

Steps to Reproduce:
1.open extremely long scroll-list (longer than what fits on the screen)
2.try to scroll in it with scroll-wheel or via down-arrow button
3.
  
Actual results:
see above

Expected results:
both methods should allow me to select items in the list without retreating to keyboard

Additional info:
Filed already upstream as https://bugzilla.gnome.org/show_bug.cgi?id=674653