title: Make some elements not selectable jquery ui
body: <p>i have some <code>td</code>s in a <code>table.</code>
  all tds are <code>selectable</code>.</p>
  
  <pre><code> &lt;table id="selectable"&gt;
                                &lt;tr&gt;
                                &lt;td class="ui-state-default" &gt;&lt;/td&gt;
                                &lt;td class="ui-state-default" &gt;&lt;/td&gt;
                                &lt;td class="ui-state-default" &gt;&lt;/td&gt;
                                &lt;/tr&gt;
                                &lt;tr&gt;
                                &lt;td class="ui-state-default" &gt;&lt;/td&gt;
                                &lt;td class="ui-state-default" &gt;&lt;/td&gt;
                                &lt;td class="ui-state-default" &gt;&lt;/td&gt;
                                &lt;/tr&gt;
                                &lt;tr&gt;
                                &lt;td class="ui-state-default" &gt;&lt;/td&gt;
                                &lt;td class="ui-state-default" &gt;&lt;/td&gt;
                                &lt;td class="ui-state-default" &gt;&lt;/td&gt;
                                &lt;/tr&gt;                             
                              &lt;/table&gt;
  </code></pre>
  
  <p>i want some <code>td</code>s as not selectable. how to make it.please help</p>