title: How to draw block diagrams in java?
body: <p>I need to have a <code>GUI</code> like this:</p>
  
  <p><img src="https://i.stack.imgur.com/2hRqL.png" alt="Block Diagram"></p>
  
  <p>Here all the rectangles must be buttons.  How can I achieve this?  Suggest me some tools like <code>JFormDesigner</code>.</p>