Filter panel
The Filter panel is not displayed well after certain operations. See a picture below. This issue occurs also in the other tools.
Steps to reproduction:
1st Run the Duplicate File Finder,
2nd Show the Filter panel,
3rd Click Select -> All,
4th The Filter panel is not displayed well,
5th Hold your mouse over the Filter panel,
6th Click Select -> None, or Inverse, or Highlighted,
7th The Filter panel is not displayed well.
Edit: Probably only on Windows Vista SP2...