I am trying to set up some of my old dark curtains. I can't keep them permanently installed (rented flat), so I need to put it up for each session. I want to block off a doorway but the cloth that I used before just sags down and lets light in, mainly because of the curtain wire I am using. Earlier this was not a problem, but now I need some other, better way to putting it up. Tried sticky stuff and other things before, but it fell down and was no good.

Any good ideas? Pictures are always welcome.