title: How to implement content assist's documentation popup in Eclipse RCP
body: <p>I have implemented my own editor and added a code completion functionality to it. My content assistant is registered in source viewer configuration like this:</p>
  
  <pre class="lang-java prettyprint-override"><code>public IContentAssistant getContentAssistant(ISourceViewer sourceViewer) {
      if (assistant == null) {
          assistant = new ContentAssistant();
          assistant.setDocumentPartitioning(getConfiguredDocumentPartitioning(sourceViewer));
          assistant.setContentAssistProcessor(getMyAssistProcessor(),
                  MyPartitionScanner.DESIRED_PARTITION_FOR_MY_ASSISTANCE);
          assistant.enableAutoActivation(true);
          assistant.setAutoActivationDelay(500);
          assistant.setProposalPopupOrientation(IContentAssistant.PROPOSAL_OVERLAY);
          assistant.setContextInformationPopupOrientation(IContentAssistant.CONTEXT_INFO_ABOVE);
      }
      return assistant;
  }
  </code></pre>
  
  <p>When I press <kbd>Ctrl</kbd> + <kbd>SPACE</kbd> inside the desired partition, the completion popup appears and works as expected.</p>
  
  <p>And here's my question.. How do I implement/register a documentation popup that appears next to completion popup? (For example in java editor)</p>