title: Is :not(:hover) and :hover a safe way to hide accessible elements?
body: <p>Sometimes it appears helpful to make certain page elements only visible on e.g. hovers. An example is stackoverflow's "feedback - Was this post useful to you?"-widget. As those elements might be crucial to the interface, such a show-on-hover-feature should be a progressive enhancement or, in other terms, unobtrusive and degrade gracefully.</p>
  
  <p>The usual way appears to be employing javascript, e.g. hiding the elements and making them available when a parent element is hovered. The reason for that choice might be <code>:hover</code> is not support for all elements especially in legacy browsers, thereby forbidding you to hide elements in the first place up to css2. (for a js/jQuery example cf. <a href="https://stackoverflow.com/questions/6641966/jquery-showing-elements-on-hover">jquery showing elements on hover</a>)</p>
  
  <p>I wonder if you can achieve such a feature safely* with pure css3, using <code>:not(:hover)</code> and <code>:hover</code>, not affecting older browsers. As far as I can see, the requirement is that every browser supporting <code>:not()</code> must support <code>:hover</code> for all elements. According to the following sources, that appears to be the case</p>
  
  <ul>
  <li><a href="http://www.quirksmode.org/css/contents.html" rel="nofollow noreferrer">http://www.quirksmode.org/css/contents.html</a></li>
  <li><a href="http://kimblim.dk/css-tests/selectors/" rel="nofollow noreferrer">http://kimblim.dk/css-tests/selectors/</a></li>
  </ul>
  
  <p>Example implementation: <a href="http://jsfiddle.net/LGQMJ/" rel="nofollow noreferrer">http://jsfiddle.net/LGQMJ/</a></p>
  
  <p>What do you think? Any objections or other sources?</p>
  
  <p>*by safely I mean the browser should always show all elements as a last resort.</p>