title: How to prevent sorting dynamically
body: <p>In my <code>AgGrid</code> I am marking the grid as <code>dirty</code> if I have a modification in it. If it's <code>dirty===true</code> then I want to popup a dialog if somebody is trying to sort the columns asking whether to really sort the column. So I need a way <strong>how to suppress sorting</strong>. </p>
  
  <p>I think I could use an event <code>beforeSortChanged</code> but it doesn't provide me with any params. I haven't found any handlers to suppress sorting/filtering either. Is there any means to do it?</p>