Version:            (using KDE 4.3.0)
Installed from:    Fedora RPMs

The Air Plasma theme has to large margins for taskbar items (larger than the drawn borders really are) and therefore taskbar applets that adhere the plasma margins crop text drawn inside of the task items to much.

See this example screenshot:
http://img197.yfrog.com/i/pic8w.jpg/

At the left STasks ignores the margins: notice how the p and g are drawn over the borders - ugly!
At the right Smooth-Tasks adheres the margins: notice how the text is cropped to much.

However, this could also be a bug how I read and use the margins in Smooth-Tasks (but I *very* much doubt that).
For that see the TaskItem::drawText method (especially the lines 808 and 828):
http://bitbucket.org/panzi/smooth-tasks/src/d567ac09d00f/applet/SmoothTasks/TaskItem.cpp