some vim movements cause strange content shift

[mydimension]

one poignant example is doing 'cw'

seems to only effect buffers that represent a file. i can't duplicate this in unnamed buffers (makes sense as there is nothing to autosave, perhaps?)

I'll use JSON.pm (v2.53) as an example:

Starting state (cursor position represented as [X]):

use base qw(Exporter);
@[J]SON::EXPORT = qw(from_json to_json jsonToObj objToJson encode_json decode_json);                                                                                                                                                            

BEGIN {

do a 'cw' to change the word "JSON", i end up in this state:

use base qw(Exporter);
@JSON::EXPORT = qw(from_json to_json jsonToObj objToJson encode_json decode_json);                                                                                                                                                            
[@]::EXPORT = qw(from_json to_json jsonToObj objToJson encode_json decode_json);    
BEGIN {

interestingly, if I move around (i.e. PgDn then PgUp) everything appears normal.

also, the behavior does not happen if I defocus/refocus iterm2 prior to the 'cw' command but after opening the file.

at all times, defocusing iterm2 gives the following in the status line "No matching autocommands"

[sjl]

Okay, part one of this is to silence the harmless "no matching autocommands" error. I'm making that a second ticket.

[vectorstorm]

I'm getting the same issue as mydimension. For me, it happens only when running through tmux, not when running normally in iTerm2.

It's most consistent when I press 'x' immediately after opening a file. It's interesting to note that when it happens, in addition to the changes that mydimension quoted, my (vim default) status line changes from:

JSON.pm                                                             :b1[perl] 3,0-1 All
"JSON.pm" 4L, 271C

to:

JSON.pm                                                               :b1[perl] 2,2 All
"JSON.pm[+]L, 271C                                                 :b1[perl][+        d
l                                                                             

It looks like the status line has made just barely enough space to tell me I used the 'x' command, and then printed 'dl' instead, which made the terminal scroll up one line unexpectedly. Similarly, if I use 'X', it prints 'dh', split across the two lines, producing the same apparently-scrolled terminal screen.

I've checked :map, and no, I haven't mapped x to dl, or anything weird like that. And if I use cursor keys to move the cursor around a little before editing, the problem usually doesn't happen.

I've spent the last hour or so making a reproducible test case, and I've found that the minimum setup required for me to get this behaviour is a .vimrc containing nothing but the following lines:

set showcmd
if exists('$TMUX')
    let &t_SI = "\<Esc>Ptmux;\<Esc>\<Esc>]50;CursorShape=1\x7\<Esc>\\"
    let &t_EI = "\<Esc>Ptmux;\<Esc>\<Esc>]50;CursorShape=0\x7\<Esc>\\"
endif

'showcmd' is required, in addition to both t_SI and t_EI. If any of these three are set differently, then the bad behaviour doesn't happen for me. But with all three set this way, if I edit this .vimrc from inside tmux, and then press 'x' immediately after opening the file, I get the odd screen content scrolling happening almost every time.

(So for the time being, I'm making do without 'showcmd'). Not quite sure what would cause this misbehaviour, but I thought I'd include the steps I took here, just in case they meant more to somebody else.

[aaronjensen]

see #8 for an alternative solution that doesn't require vitality.vim