Bug#858304: vim-runtime: markdown syntax highlighting (and possibly others) goes crazy and drives the terminal crazy

[James McCoy]

Control: tag -1 confirmed
Control: reassign -1 xterm
Control: retitle -1 Terminal stays bold after visual bell with bold text displayed

On Mon, Mar 20, 2017 at 10:29:20PM +0100, Francesco Poli (wintermute) wrote:
> I have experienced this bug for a fairly long time, when editing
> markdown documents with vim. It has been triggered in a seemingly
> random manner.

It's the visual bell that happens when you get to the top of the buffer
and try to keep going.  That causes Vim to send the BEL (Ctrl-G) to the
terminal.  The way the buffer is currently highlighted (some bold text)
at that point is causing xterm to get stuck.

You can reset it by Ctrl-RightClick -> "Escape Sequence".

It works fine in at least pangoterm, but I haven't tried other more
mainstream terminals.

I'm reassigning to xterm for now.  Rest of the context is below.

> I finally found a reliable way to reproduce it.
> 
> Steps to reproduce:
> 
>   0) open the attached test.md file:
> 
>      $ vim -u NONE test.md
> 
>   1) enable syntax highlighting:
> 
>      :set bg=dark
>      :syn on
> 
>   2) go to the end of the file:
> 
>      [Shift+G]
> 
>   3) go back to the beginning of the file (line by line):
> 
>      [k].....[k]     ← hold the key pressed until you reach the first line
> 
>   4) visualize file info on the status line:
> 
>      [Ctrl+G]
> 
>   5) the syntax highlighting has gone crazy (even the status line is
>      in boldface!): see the attached screenshot
>      wrong_vim_syntaxmarkdown.png
> 
>   6) exit from vim:
> 
>      :q
> 
>   7) the terminal (xterm), or rather the shell (bash), has also gone
>      crazy (it now prints everything in boldface by default): see
>      the attached screenshot
>      wrong_vim_syntaxmarkdown2.png
> 
>   8) the terminal won't come back to normal behavior until I quit it;
>      another trick to regain the normal behavior of the terminal is
>      opening test.md again, enable syntax highlighting, and exit vim
>      (steps 0, 1, and 6 above)

Cheers,
-- 
James
GPG Key: 4096R/91BF BF4D 6956 BD5D F7B7  2D23 DFE6 91AE 331B A3DB