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This works on windows, but not on mac.

It would be nice to have, it's easier to recognise shots by their thumb than by their number/name.

See screenshot:

I must agree with you, but unfortunately, this kind of feature is a nightmare to develop. (Or, at least, it was a nightmare : I don't know if it's still the case.)

If I remember well, the way to do it is different on Mac OS 10.6 10.7 10.8 and 10.9 ... so it's not for now.