Desktop Icon Size

[Spandex]

In the Configure Dexpot > Tools menu there's a box for changing the Desktop Icons. However, all options except one (i.e. "Hide icon titles") are dimmed out and cannot be applied.
As I would like to change the icon sizes for one of the Dexpot desktops I wonder what you have to do to get especially the Icon size option working?
Thanks for your advice!

[Patrick]

It's a very old option that only works on Windows XP.