Vim normal and insert mode cursor not changing in GNU screen

Question

I use vim in a few different contexts; typically, I like to put this in my .vimrc:

let &t_ti.="\<Esc>[1 q"
let &t_SI.="\<Esc>[5 q"
let &t_EI.="\<Esc>[1 q"
let &t_te.="\<Esc>[0 q"

This makes it so that insert and normal mode use different cursors (normal mode is a block cursor and insert mode is a vertical line). This works for me in mintty with cygwin, xterm, and also rvxt just fine. However, whenever I use GNU screen, my cursor no longer changes. I've seen references to fixing this for tmux (for instance here: Cursor shape under vim + tmux), but nothing I've tried for Screen has worked. For now, I'm using this in my .vimrc:

"Underline currently edited line
if !has("gui_running")
    :autocmd InsertEnter * set cul
    :autocmd InsertLeave * set nocul
endif

That makes it so that when in insert mode the current line is underlined (the :has("gui_running") prevents it from taking effect in gvim). I also use set laststatus=2 to keep the status bar on the bottom, which also helps. I just wish it worked a bit more like gvim. Has anyone found a fix for this?

Answer 1

I think I figured it out, although I don't totally understand the fix. This appears to work for mintty, xterm, and rxvt:

" Set up vertical vs block cursor for insert/normal mode
if &term =~ "screen."
    let &t_ti.="\eP\e[1 q\e\\"
    let &t_SI.="\eP\e[5 q\e\\"
    let &t_EI.="\eP\e[1 q\e\\"
    let &t_te.="\eP\e[0 q\e\\"
else
    let &t_ti.="\<Esc>[1 q"
    let &t_SI.="\<Esc>[5 q"
    let &t_EI.="\<Esc>[1 q"
    let &t_te.="\<Esc>[0 q"
endif

This leans on your screenrc having something like "term screen" or "term screen-256color" so that the vimrc file can identify which terminal you're on. The only remaining terminal I use regularly where this doesn't work is PuTTY, but I think it literally doesn't support terminal commands to change the cursor shape. Mintty was forked from PuTTY a while back, and I saw here (https://www.cygwin.com/ml/cygwin-announce/2009-07/msg00011.html) that DECSCUSR support was added to mintty after that fork.

This is good enough for me - if I'm ssh'ing into a machine where I really want my block cursor in Vim, I guess I can either cygwin/ssh or PuTTY/XMing/rxvt my way through it instead of PuTTY.