Update README.mkd: off → no for signcolumn

The valid values for `signcolumn` are '`auto`' ,'`no`', '`yes'` and '`number'` but not '`off'`:

```
E474: Invalid argument: signcolumn=off
```

Thanks!

README.mkd

@@ -81,7 +81,7 @@ Second, ensure your `updatetime` and `signcolumn` options are set appropriately.
 
 When you make a change to a file tracked by git, the diff markers should appear automatically after a short delay.  The delay is governed by vim's `updatetime` option; the default value is `4000`, i.e. 4 seconds, but I suggest reducing it to around 100ms (add `set updatetime=100` to your vimrc).  Note `updatetime` also controls the delay before vim writes its swap file (see `:help updatetime`).
 
-The `signcolumn` option can have any value except `'off'`.
+The `signcolumn` option can have any value except `'no'`.
 
 
 ### Windows
@@ -533,6 +533,8 @@ let g:gitgutter_async = 0
 
 Add `let g:gitgutter_preview_win_floating = 1` to your `~/.vimrc`.  Note that on Vim this prevents you staging (partial) hunks via the preview window.
 
+On Neovim, the preview hunk command will move the cursor into the floating window if it is already open.
+
 
 #### The appearance of a floating/popup window for hunk previews
 

autoload/gitgutter/diff.vim

@@ -116,7 +116,8 @@ function! gitgutter#diff#run_diff(bufnr, from, preserve_full_diff) abort
 
     " Write file from index to temporary file.
     let index_name = gitgutter#utility#get_diff_base(a:bufnr).':'.gitgutter#utility#base_path(a:bufnr)
-    let cmd .= gitgutter#git(a:bufnr).' --no-pager show --textconv '.index_name.' > '.from_file.' || exit 0) && ('
+    let cmd .= gitgutter#git(a:bufnr).' --no-pager show --textconv '.index_name
+    let cmd .= ' > '.gitgutter#utility#shellescape(from_file).' || exit 0) && ('
 
   elseif a:from ==# 'working_tree'
     let from_file = gitgutter#utility#repo_path(a:bufnr, 1)
@@ -129,7 +130,8 @@ function! gitgutter#diff#run_diff(bufnr, from, preserve_full_diff) abort
     let cmd .= ' -c "diff.noprefix=false"'
     let cmd .= ' -c "core.safecrlf=false"'
   endif
-  let cmd .= ' diff --no-ext-diff --no-color -U0 '.g:gitgutter_diff_args.' -- '.from_file.' '.buff_file
+  let cmd .= ' diff --no-ext-diff --no-color -U0 '.g:gitgutter_diff_args
+  let cmd .= ' -- '.gitgutter#utility#shellescape(from_file).' '.gitgutter#utility#shellescape(buff_file)
 
   " Pipe git-diff output into grep.
   if !a:preserve_full_diff && !empty(g:gitgutter_grep)

autoload/gitgutter/hunk.vim

@@ -359,6 +359,11 @@ endfunction
 
 
 function! s:preview(hunk_diff)
+  if g:gitgutter_preview_win_floating && exists('*nvim_set_current_win') && s:winid != 0
+    call nvim_set_current_win(s:winid)
+    return
+  endif
+
   let lines = split(a:hunk_diff, '\r\?\n')
   let header = lines[0:4]
   let body = lines[5:]

doc/gitgutter.txt

@@ -201,11 +201,13 @@ Commands for operating on a hunk:~
 :GitGutterUndoHunk      Undo the hunk the cursor is in.
 
                                               *gitgutter-:GitGutterPreviewHunk*
-:GitGutterPreviewHunk   Preview the hunk the cursor is in.
+:GitGutterPreviewHunk   Preview the hunk the cursor is in or, if you are using
+                        floating preview windows in Neovim and the window is
+                        already open, move the cursor into the window.
 
                         To stage part of the hunk, move to the preview window,
-                        delete any lines you do not want to stage, and
-                        |GitGutterStageHunk|.
+                        delete any lines you do not want to stage, and |write|
+                        or |GitGutterStageHunk|.
 
                         To close a non-floating preview window use |:pclose|
                         or |CTRL-W_z| or |CTRL-W_CTRL-Z|; or normal window-

plugin/gitgutter.vim

@@ -341,8 +341,18 @@ augroup gitgutter
   autocmd BufFilePre  * call s:on_buffilepre(expand('<abuf>'))
   autocmd BufFilePost * call s:on_buffilepost(expand('<abuf>'))
 
-  autocmd QuickFixCmdPre  *vimgrep* let b:gitgutter_was_enabled = gitgutter#utility#getbufvar(expand('<abuf>'), 'enabled') | GitGutterBufferDisable
-  autocmd QuickFixCmdPost *vimgrep* if b:gitgutter_was_enabled | GitGutterBufferEnable | endif | unlet b:gitgutter_was_enabled
+  autocmd QuickFixCmdPre *vimgrep*
+        \ if gitgutter#utility#getbufvar(expand('<abuf>'), 'enabled') |
+        \   let s:gitgutter_was_enabled = expand('<abuf>') |
+        \ else |
+        \   let s:gitgutter_was_enabled = 0 |
+        \ endif |
+        \ GitGutterBufferDisable
+  autocmd QuickFixCmdPost *vimgrep*
+        \ if s:gitgutter_was_enabled |
+        \   call gitgutter#buffer_enable(s:gitgutter_was_enabled) |
+        \ endif |
+        \ unlet s:gitgutter_was_enabled
 augroup END
 
 " }}}