title: Blocking operation in custom SWT component
body: <p><strong>What is the best way to run long operations within custom SWT components?</strong></p>
  
  <p><strong>Objective:</strong> I want to build a mail state indicator with SWT. Basically, it should constantly poll a service and display an image depending on the state flag that is returned (for sake of simplicity, lets say <code>MailState.NO_MAILS</code> or <code>MailState.NEW_MAILS</code>).</p>
  
  <p><strong>Problem:</strong> I'm aware of the fact, that I should not run a blocking operation in the SWT GUI thread.</p>
  
  <p>So what is the best way to make my component either poll a service asynchronously every x seconds or (maybe) use a blocking <code>Future</code> without making my interface freeze?</p>