Funny you should ask... I was just looking at mine today thinking its a little annouying that the triangle like side piece wont stay put. I did try a curtain hook stuck into the rat fur but that did not work.
Today I was thinking that getting a very short piece of elastic cord and securing one end to the side of the cabinet in the inside, then running it through a small hole in the triangle-like side panel, then stretching it a little and securing it with a cord lock like this:
Its the same concept as a outdoor water spigot cover...
https://www.homedepot.com/p/Hard-Fau...1981/204759083