xterm-keys by default, generates \033[1;3A instead of
\033\033[OA. Unfortunately this confuses vi, which doesn't understand
xterm keys and now sees Escape+Up pressed within escape-time as Escape
followed by A.
The issue doesn't happen in xterm itself because it gets the keys from X
and can distinguish between a genuine M-Up and Escape+Up.
Because xterm can, tmux can too: xterm will give us \033[1;3A (that is,
kUP3) for a real M-Up and \033\033OA for Escape+Up - in fact, we can be
sure any \033 preceding an xterm key is a real Escape key press because
Meta would be part of the xterm key instead of a separate \033.
So change tmux to recognise both sequences as M-Up for its own purposes,
but generate the xterm version of M-Up only if it originally received
the xterm version from the terminal.
This means we will return to sending \033\033OA instead of the xterm key
for terminals that do not support xterm keys themselves, but there is no
practical way around this because they do not allow us to distinguish
between Escape+Up and M-Up. xterm style escape sequences are now the de
facto standard for these keys in any case.
Problem reported by jsing@ and subsequently by Cecile Tonglet in GitHub
issue 907.
and not have to wait for an update when they change pane, we allow
commands to run more than once a second if the expanded form
changes. Unfortunately this can mean them being run far too often
(pretty much continually) when multiple clients exist, because some
formats (including #D) will always differ between clients.
To avoid this, give each client its own tree of jobs which means that
the same command will be different instances for each client - similar
to how we have the tag to separate commands for different panes.
GitHub issue 889; test case reported by Paul Johnson.
