There is already an integration with blocktrades on steemit (is kind of like shiftshape), so that could be also reused for this tipping button.

I guess the whole point of Steem was that you could do microtipping basically. Fees on Bitcoin already already relatively high for microtipping, but if we are talking about people wanting to tip "larger" amounts, I guess it could work.

An additional benefit: it would also make it possible for people who are not on Steemit and don't want to open an account here, to tip authors here anyway.