[uranusjr]

It has been around for as long as I can remember, and I have been using Mac since 10.3.

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Edit: Thinking about it a bit more, it might not be that long since I wasn’t into programming back then and hidden files meant little to me. The first time I used it was probably around Leopard.

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Edit 2: It seems like the feature debuted in Lion (10.7). This would make sense since Finder was overhauled in that version to add several features.