Selection problem in Firefox 24 (DOM version)
Focus must be on the element getting the selection. This fiddle uses rangy to show the problem.
HTML
<p id="q" contenteditable="true">text</p>
<input id="input" />
<button id="forward">Forward</button>
<button id="backwards">Backwards</button>
<button id="backwards-wa">Backwards Workaround</button>