Since bitcoin addresses are hashes of public keys and not public keys as such, if one wanted to craft a message that could be decrypted by the generator of an address, that can't be done just with an address. But after the generator of an address has spent something that was received there, which requires presenting the public key (or does it?) publicly, is that public key part of the public record so it can be used for direct message encryption?
And is there a standard way to perform such message encryption, analogous to opaque PGP blocks, and supported by UI panels in bitcoin-qt where one can paste blocks of plain (with intended recipient) or ciphertext (directed to one of one's own addresses) and see plaintext or a copyable opaque block?