Disallow insert mode in the NERDTree

Author: wycats

plugin/NERD_tree.vim

@@ -167,6 +167,9 @@ command! -n=0 -bar NERDTreeFind call s:findAndRevealPath()
 augroup NERDTree
     "Save the cursor position whenever we close the nerd tree
     exec "autocmd BufWinLeave ". s:NERDTreeBufName ."* call <SID>saveScreenState()"
+
+    "disallow insert mode in the NERDTree
+    exec "autocmd BufEnter ". s:NERDTreeBufName ."* stopinsert"
     "cache bookmarks when vim loads
     autocmd VimEnter * call s:Bookmark.CacheBookmarks(0)