I would suggest a copy buffer in JOE. Right now the only way to do a block copy is to go through the following:
Mark block of text: ^K^B
End marking of block: ^K^K
move somewhere and copy block with ^K^C
BUT the block must remain highlighted and not deleted because once deleted with ^K^Y, ^K^C says that there is no block to copy.
Right now I emulate the copy buffer by using the kill buffer by replacing the original command associated with ^K^C: blkcpy with yank. However this is not ideal because when I delete any other character, it goes into the kill buffer and I lose my original text which I had marked and deleted. I'd like to suggest a copy buffer so that this will work correctly.