This is a remix of the filament clip with screw, Kimframes allowed me to do the remix. I keep his license terms also for this design as-is.
The basic idea is taken from the curtain clip by pipersw.
Print a few clips (one every 30cm) and screws, attach a tesa powerstrip to the lower side, and stick the curtain clip to the top of the wardrobe.
Fix the curtain to the back of the wardrobe using the screws.
To get neat sides, you can fix the curtain additionally with needles/pins. (Pins are not good on the top as they tear the curtain cloth in case there is a pull on the curtain)
The clip was redesigned to fit a Tesa Powerstrip to mount on a wardrobe. It was also shortened, and the screw was shortened as well.