screen+mc: keys up/down skipping

[mc-butler]

Important

This issue was migrated from Trac:

Origin	https://midnight-commander.org/ticket/3344
Reporter	shamilbi (shamilbi@….com)
Mentions	egmont@….com (@egmontkob)
Keywords	mc, screen, up, down

since version 4.8.9 mc skips some keys up/down
1) start screen (or tmux)
2) start mc (version > 4.8.8)
3) press UP (or DOWN) several times (some of them will be skipped)

[mc-butler]

Changed by egmont (@egmontkob) on Feb 20, 2015 at 16:11 UTC (comment 1)

• Cc set to egmont@….com

I don't face this with screen/tmux, however, I've found something probably closely related.

mc under st (suckless's terminal) doesn't immediately react to keypresses, you need to press e.g. the Down arrow 3 times and then suddenly it goes down by 3 lines, making it totally unusable.

This behavior also started with mc-4.8.9. Looking at the NEWS file, #2988 seems to be the only relevant change. Probably screen/tmux/st send the characters with some weird timing (e.g. a minor pause between the bytes) which causes trouble.

[mc-butler]

Changed by egmont (@egmontkob) on Feb 20, 2015 at 17:06 UTC (comment 2)

@shamilbi:

What's your $TERM? Does the bug occur to you if you set it to xterm? (Normally it should be screen or screen-256color.)

Do you have mouse working inside screen? Is your mc buggy if you start without mouse support ("mc -d")?

Launch "strace -o /tmp/mctrace mc" and from another terminal check the file size of /tmp/mctrace a few times. Does it settle at a certain file size, or does it grow endlessly even when you don't use mc?

In st I've noticed the following (note: st sets TERM=st-256color, and does not support mouse at all):

When stracing, the trace reveals continuous activity, including trying to open /dev/gpmctl, even when mc seems to be idle.

Either setting TERM=xterm, or starting as "mc -d" makes the bug go away: input works as expected, and its strace only grows when you do something inside mc.

[mc-butler]

Changed by shamilbi (shamilbi@….com) on Feb 21, 2015 at 14:38 UTC (comment 3)

configure option --with-gpm-mouse=no solved the problem, checked it on TERM=linux and TERM=xterm