I use byobu in tmux mode. In screen I can do this:
Ctrl+a [, move to line, Y, Ctrl+a ]
"Y" copys the whole line into the clipboard. I am looking to something similar in byobu in tmux mode. The only thing I found is:
Ctrl+a/b (depends on your setting) + [, move to line, 0, space, $, enter, Ctrl+a/b + ]
But I feel like that is a lot of hard to reach keystrokes, Y is much easier.