title: Make Alt_R an Alt (A-) modifier key (instead of a Meta (M-) modifier key)
body: <p>I want to set <code>Alt_L</code> as <strong>META</strong> (ie. M- in emacs) but <code>Alt_R</code> as <strong>ALT</strong>.  How do I modify <code>.Xmodmap</code> and/or <code>.emacs</code> to achieve this?</p>