How to assign customer Theme in 7.5. to Desktop ?

Hello,

We have upgraded our Test Portal from 7.0 to 7.5. Somehow, after implementing a patch, we managed to import our old customer Theme (created in 7.0) into 7.5. So we are now able to change it in the UI Theme Designer.

Now we face the problem that the themes build within the UI Theme Designer are stored in the "Web Ressource Repository" instead of Portal Content Management (folder themes). But the official doku still says that the assignment from Theme to Desktop should be done under "System Administration --> System Configuration --> Portal Display --> Desktop & Display Rules". (p.s. we use the classic Desktop and Frameworkpage). There only the old themes are available, but not any theme created in UI Theme Designer.

So does anybody know how to assign our customer theme in "Desktop & Display Rules" to our (classic) Desktop in 7.5. ?

Thank you and Best Regards,

Andreas