title: Mac vim can not send R code
body: <p>After install the <code>R.vim.plugin</code>, it works smoothly to start R by <code>&lt;mapleader&gt;rf</code> as well as send R code like <code>&lt;mapleader&gt;se</code>. HOWEVER, when I open another R file at the same time, then I can't send R code to R gui anymore. There's a message say:</p>
  
  <pre><code>Did you already start R?
  </code></pre>
  
  <p>The R Gui is certainly started and why it doesn't work for the second macvim file? </p>