Function attachVimMap

src/codemirror.js:9598–9604

(cm, prev)

        leaveVimMode(cm, false);
    }
    function attachVimMap(cm, prev) {
      if (this == CodeMirror.keyMap.vim)
        CodeMirror.addClass(cm.getWrapperElement(), "cm-fat-cursor");

      if (!prev || prev.attach != attachVimMap)
        enterVimMode(cm);
    }

    // Deprecated, simply setting the keymap works again.
    CodeMirror.defineOption('vimMode', false, function(cm, val, prev) {