Stripey (who I always suspected of being an evil genius behind her shy demeanour) has learned how to open tubs. Last night I gave the cats a couple of treats that come in a tube with a plastic sealable cap. This morning the tube was lying open with the cap on the top of the cat scratcher.
I'm accusing her because Snowcat is much less naughty, wasn't that into those particular treats, and also when DH asked her she definitely shook her head.
She has also learned how to open the big wooden cupboard in our living room and we discovered that she has spent the last few days hiding behind the bags of knitting yarn I store in it. Fortunately she doesn't seem interested in pulling out the yarn and playing with it, just sitting on the bags.