In Estudio: Tools ⇒ Preferences shows the following

Usually, the external editor command might show: term -geometry 100×40 -e vi +$line $target

Vim is a popular editor that also has an Eiffel mode. On Centos7 on Prism use: gvim +$line $target

On the Mac, one may install MacVim, for example.

In that case, enter: /Applications/MacVim.app/Contents/bin/mvim +$line $target

File ⇒ External Editor then produces

Syntax ⇒ Convert to HTML creates an HTML file with appropriate syntax colouring that can also be inserted in Word file.

A possible $HOME/.vimrc file is shown below.

set nocompatible                " choose no compatibility with legacy vi
syntax enable
set encoding=utf-8
set showcmd                     " display incomplete commands
filetype plugin indent on       " load file type plugins + indentation


"" Searching
set hlsearch                    " highlight matches
set incsearch                   " incremental searching
set ignorecase                  " searches are case insensitive...
set smartcase                   " ... unless they contain at least one capital letter

"" Whitespace
set nowrap                      " don't wrap lines
set backspace=indent,eol,start  " backspace through everything in insert mode
set tabstop=4       " The width of a TAB is set to 4.
                    " Still it is a \t. It is just that
                    " Vim will interpret it to be having
                    " a width of 3.
set shiftwidth=4    " Indents will have a width of 4
set softtabstop=4   " Sets the number of columns for a TAB
set expandtab       " Expand TABs to spaces

"" Font Size
set guifont=Menlo\ Regular:h18