[screen-devel] [bug #49883] Run mc inside screen + resize terminal + ctrl-a esc + pgup pgup pgup = bug

[Askar Safin]

URL:
  <http://savannah.gnu.org/bugs/?49883>

                 Summary: Run mc inside screen + resize terminal + ctrl-a esc
+ pgup pgup pgup = bug
                 Project: GNU Screen
            Submitted by: safinaskar
            Submitted on: Mon 19 Dec 2016 01:42:30 AM GMT
                Category: Program Logic
                Severity: 3 - Normal
                Priority: 5 - Normal
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 4.4.0
           Fixed Release: None
         Planned Release: None
           Work Required: None

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Details:

(All described behavior happens in "normal" terminal such as gnome-terminal
and not in "dumb" terminal such as linux console)

Run screen, then run mc in it, then exit from mc. You will see this:

[ Lot of empty space ]
$ _

So, all previous commands and their output moved up (to scrollback) and now
they are accessible using ctrl-a esc only. What should be instead? Instead
terminal should come to state in which it was before mc startup. I. e. all
output should be here. I should see this:

$ mc

$ _

I. e. I should see "mc" command I used to run mc, then one empty line and the
current line with cursor. I. e. I should see same that happen without screen
involved. tmux has no this bug.

Okey, now let me say about next bug. Open screen, then open mc inside it. Then
resize your outer terminal (this will cause resizing of screen, of course).
Then exit from mc, type ctrl-a esc and type pgup several times. You will see
that your scrollback contains a lot of copies of mc (with different sizes).
This is wrong. Scrollback should contain same text it contained before
starting of mc. Again, tmux has no this bug.

But when fixing this bug be careful not to introduce yet another bug. tmux has
bug:

* Start tmux
* Type into it: "for ((I = 1; I <= 100; ++I)) { echo $I; }; mc" and press
Enter
* Ctrl-b " (tell tmux to open new pane, this will make mc smaller)
* Ctrl-b ; (tell tmux to switch to top pane, i. e. to mc)
* f10 (or esc 0) (exit from mc)

Now I see:

82
83

34  2015-07-09 19:38:32  ~$ _

And I expected to see:

99
100

34  2015-07-09 19:38:32  ~$ _

So, tmux "eats" numbers 84..100.
So, tmux has this bug and screen has not. When you fix bugs described at the
beginning of this report, be careful not to introduce this tmux's bug I
described here.

$ screen --version
Screen version 4.04.00 (GNU) 19-Jun-16




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