When code is folded in, the divider is drawn on the bottom pixel of the current line, completely obscuring underscores in many fonts, making the underscores appear to be spaces instead.
Use the Ubuntu Sans Mono font or any other affected font.
Create a new C source file.
Write a simple function with an underscore in the declaration.
Fold in the function by clicking the "-" next to the declaration.
All of the underscores in the declaration should look like spaces instead of underscores.
Add a few pixels of padding between the bottom of the line and the divider.
Reproducible with a fresh build from the git repo.
OS: Ubuntu 10.04 Server
Version: 1.22 (built on 3/26)