This is a great tab. Excellent work. I like how (per the example on ganja1447's profile) it will take the first note on other challenge caches as potentially being evidence that I've already signed, but also give me the ability to modify that list for those I've just left a note on.
One note, it looks accurate for nearly all challenge caches I've done, but it does have one false positive: GCM8MG, Berserkr's Challenge, is on my list but isn't a challenge cache, just a very challenging mystery cache. If there's some way to flag such caches, similar to excluding traveling caches from statistics, this cache at least needs such a flag.
