title: Sublime Text detect overwrite mode
body: <p>I am trying to write a plugin to support a vim-like replace mode in <a href="http://www.sublimetext.com/" rel="noreferrer">Sublime</a>.
  To accomplish this, there are a couple things that I need to be able to do:</p>
  
  <ol>
  <li>enable/disable overwrite mode. (not <code>toggle_overwrite</code>).</li>
  <li>detect if overwrite mode is enabled.</li>
  </ol>
  
  <p>Item 2 is more important because I could always detect and toggle if necessary.</p>
  
  <p>How can I detect if overwrite mode is enabled?</p>