u can go to hardware shop to buy a plastic white col plug, don't know what it call. Tell the shop that u want to screw something into plster ceiling or partition, the plug is around RM0.30/ pc.

haha, normally i call it butterfly.
have to make sure your curtain is not thick and heavy if u use this plug

normally if ppl use this pelmet design for curtain, they will ask the plaster ceiling guy to add a timber on top of plaster ceiling, so that can straight screw into the timber above.

pelmet