prudnik's dashboard

How do i change the target operating systems for my Add-On?
As a developper I have an add-on in that sand box. Initially I thought it would work only under Windows. But recently I found out, that it works under Linux as well. Somebody on the Net, who tried to download my add on working on a Linux machine, told me, that she could not.
That's fine so far. But now I would link to change that and enable a Linux download as well.
The problem is, that I do not see, how to do this on the Developer site.
If sombody could help with this.