I tried deleting the entire configuration directory and reinstall slickedit, no difference (I don't have any workspaces defined, so no files to delete there). I have also tried running the v17 beta which also did similar things, expect it printed an error on the console:
QFont::setPointSize: Point size <= 0 (0), must be greater than 0
QFont::setPointSize: Point size <= 0 (-1), must be greater than 0
... (keeps going, getting more and more negitive).