I just downloaded the Effect Size Generator software to calculate some Cohen's d values. The program does not allow me to enter a negative sign in the Mean fields, so I can not enter my true group mean values. Is there a reason why it doesn't allow negative values? There should be no statistical reason to exclude negative group means from calculation as I have used other Cohen's d calculators successfully with negative values before.

Also, as a side question, is the "Extra Statistics" tab only present on the Pro edition? I downloaded it to test out the repeated-measures effect size calculations, but the free edition doesn't appear to have an extra statistics tab at all.