title: How to show error mark beside SWT widgets?
body: <p>On a project based on eclipse RCP:</p>
  
  <ol>
  <li><p>Using SWT and eclipse RCP I want to show error or info mark exactly the same as the following pictures. When the mouse pointer hovers the error mark, a popup shows the reason. I need this capability to show errors or warnings to the user. 
  <img src="https://i.stack.imgur.com/7QI9L.jpg" alt=""></p>
  
  <p><img src="https://i.stack.imgur.com/F5YPX.jpg" alt=""></p></li>
  <li><p>It would be very nice to simultaneously have the same error in the problems view.
  <img src="https://i.stack.imgur.com/5Gq4H.jpg" alt=""></p></li>
  </ol>