Butane lighter reload interrogate? If a butane lighter doesn't have something to let you know the...

If a butane lighter doesn't have something to let you know the even of the fuel, how can you tell when the lighter is full while refilling it? I don't know if over satisfying can cause a problem or not so I want to know if there is a better instrument than just waiting for the gas to jet out the sides of the replenish can.
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Answers:    I think the only course you know for sure if the lighter is full of butane is for it to spurt out when full and I don't believe it hurts anything for it to do that.