Description of problem:
When you scroll down in vte slowly, it fails to properly render the
individual lines coming from the bottom of the gnome-terminal. 
vte-0.11.11-14 and vte-0.11.11-6 are equally bad behaving in this regard.

Version-Release number of selected component (if applicable):
vte-0.11.11-14

How reproducible:
Always

Steps to Reproduce:
1. gnome-terminal
2. Open more than one tab.
3. Create multiple screens full of text.
4. Scroll up.
5. Scroll down slowly by clicking on the vertical scroll down button.

Actual Results:
Lines coming from the bottom do not render properly.

Expected Results:
Should render properly.