drop down list boxes (kinda like <select> in html forms) display 
vertically misaligned items when the list box doesn't fit the screen. 
usually when the drop down list box touches the bottom of the screen, it 
adjusts and goes up, but the items (text/lines) are not aligned to the 
list box window but the top item is aligned to where the mouse was 
clicked. it produces a scroll item at the bottom of the box but the text 
or lines are still mis aligned.

to reproduce it:
1. resize your screen to 800x600 or smaller.
2. open gimp.
3. click paint tool.
4. move the toolbox window down a little bit, but not that the 'Mode' 
drop down list box is covered.
5. click the 'Mode' drop down list box.

Note: i didn't change any settings after installing.