In response to the wallet,
yes, the log-in sequence is quite secure, but it's a hassle for many users and it's
quite confusing with all the same repeating colors and such.
The wallet is far from finished. That login sequence you see is basically all I have so far, and it is only experimental. The most common login method right now seems to be the ~12 word passphrases, but I thought this grid sequence was not any harder to remember and would easier to input (particularly on mobile). It is not final, and I am completely open to suggestions for other login methods.
Great to see that more block explorers are coming live. I'm a little confused about how balance is shown on mychain.io. I was testing with an address where the final balance is 50.02498463
BTC. But when I'm checking
http://mychain.io/address/12c6DSiU4Rq3P4ZxziKxzrL5LmMBrzjrJX it is showing the following...
Received: 0.02 BTC
Possibly received: 0.004984630000000001 BTC
How do I know the spendable amount of an address from the above data ?
I chose to display data with an accurate description, rather than use misleading terms such as "from address" and "address balance". Deciding the terminology was partly inspired and assisted by luke-jr, but I agree with the decisions I made.
The 'received' value is the largest amount paid to an address by any single confirmed transaction. Any extra transactions are added to the 'possibly received' value. This is because addresses should be used as one-time payment destinations, not as accounts or wallets. Address reuse is bad for privacy as well as security.
That specific address you linked to does not include the generation transaction it should have received in
the second block of the chain. That's a bug you just found, and I'm looking into it right now. It seems like it applies to more than just that block. I've
marked the issue on Github and will be fixing it ASAP. Thank you very much for reporting it!
Edit: To clarify my answer to your last question, mychain.io does not show the spendable amount an address has because an "address balance" is a misleading term that encourages address reuse (bad). Balances should be displayed on a wallet/account level by your software wallet.