title: Whats the equivalent for ng-grid's "beforeSelectionChange" in ui-grid?
body: <p>In <code>ng-grid</code>, I used to use <code>beforeSelectionChange</code> in the following way:</p>
  
  <p>When the user selects a row, an ajax call is performed. While the ajax call is happenning I set <code>$scope.doingAjaxCall = true</code>, and to prevent the user from changing the selection, I had this in the grid definition:</p>
  
  <pre><code>beforeSelectionChange: function () {
      return !($scope.doingAjaxCall);
  },
  </code></pre>
  
  <p>which locks/freezes the selection if the ajax call is happenning.</p>
  
  <p>Now, in <code>ui-grid</code> (aka ng-grid 3), <strong>I don't know whats the equivalent for <code>afterSelectionChange</code>.</strong></p>
  
  <p>In this section of the documentation:<br>
  <a href="http://ui-grid.info/docs/#/api/ui.grid.selection.api:PublicApi" rel="nofollow">http://ui-grid.info/docs/#/api/ui.grid.selection.api:PublicApi</a><br>
  I see two events:</p>
  
  <ul>
  <li><code>rowSelectionChanges</code> </li>
  <li><code>rowSelectionChangedBatch</code>.</li>
  </ul>
  
  <p>These seem to be the equivalent of the old <code>afterSelectionChange</code></p>
  
  <p>And in this section of the documentation:<br>
  <a href="http://ui-grid.info/docs/#/api/ui.grid.selection.service:uiGridSelectionService" rel="nofollow">http://ui-grid.info/docs/#/api/ui.grid.selection.service:uiGridSelectionService</a><br>
  I see these two methods that seem to be related to the need:</p>
  
  <ul>
  <li><code>raiseSelectionEvent(grid, changedRows, event)</code></li>
  <li><code>decideRaiseSelectionEvent(grid, row, changedRows, event)</code></li>
  </ul>
  
  <p>But I don't understand how to use them</p>
  
  <p><strong>Important note:<br/></strong>
  I'm using <code>multiSelect: false</code> (ie: only one row can be selected)</p>