While I agree this is extremely impressive, when I'm out walking, I'm not going to be looking for a convenient flat surface I can rest my hand on so I can type a message. It seems useless in practice.

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etrautmann 5 days ago | parent [-]

That's not a limitation - it works in the air, on your leg, other hand, etc.

	▲	stavros 5 days ago \| parent [-]
		Does it? Zuckerberg looks like he had to rest his hand on that desk to write, wouldn't he have written in the air if this weren't a limitation?