Version: 0.9.1 (using KDE 4.1.2) OS: Linux Installed from: Ubuntu Packages The column containing the "active" ticks isn't shown by default and can't be selected from the "View" Menu.
The active state of words has been removed since it only caused confusion. Since lesson management is quite easy now, the feature was taken out.
I was unclear: this is a documentation bug. While the section of the help file that deals with the "active" column has been removed in the meantime, most screenshots still suggest its presence.
The docs have been updated.