The shower curtain rods in our bathrooms have been resting on the top edge of the tub surround because the rubber ends of the rods keep slipping downward no matter how tight the tensiom is set. Being drywall, too much tension long term may cause the drywall to buckle. The shower curtain is also too low.
My solution was to make 4"diameter supports to help spread the load on the drywall, and prevent slipping with less pressure on the drywall. They have been located 4" above the tub surround.
The wood is a piece of scrap red oak cut-off from previous projects. The 3d model is the rosette that I used on the back panel of my last salad bowl guitar back panel. I "chopped out" the daisy in the middle of the model in order to add a 1/2" deep pocket. I put a piece of double side carpet tape on the back side. If that doesn't prevent slipping, I'll add two small screws. Trying to avoit that though.
A simple, useful, way to make use of scrap wood.