title: Use nsIEnvironment to figure out if mouse is left or right handed
body: <p>I want to detect if the user is using their mouse with the left button being primary (e.button == 0) and right as secondary (e.button == 1). Can I do this with <code>nsIEnvironment</code>?</p>
  
  <p><a href="https://developer.mozilla.org/en-US/docs/Mozilla/Tech/XPCOM/Reference/Interface/nsIEnvironment" rel="nofollow">https://developer.mozilla.org/en-US/docs/Mozilla/Tech/XPCOM/Reference/Interface/nsIEnvironment</a></p>
  
  <p>Is it possible to figure out how many buttons the users mouse has with nsIEnvironment?</p>
  
  <p>Thanks</p>