title: Several Controllers or Presenters?
body: <p>i am working on a project for getting an overview about bank accounts and their transfers (of my own). 
  Therefore I create a BorderPane, on top there is a menu bar, on the left there is a nagivation (treeView).<br>The idea is now, when selecting on a treeItem, the content of the middle part of my BorderPane should change. 
  <br>So when I click on my first CreditCard which is listed in the Navigation Tree, an overview should appear in the middle of the BorderPane. Therefore I have created a FXML-Document. 
  <br>When I click on 'Overview', all my CreditCards should appear with an overview like 'amount at beginning of the month' and 'amount now'.
   I got a FXML for this look, too.
  The problem is: I'm not pretty sure how to handle the controls of each different FXML-File. Should each FXML-File has its own controller?<br> Or should I just use one controller to handle each interacted control and just call another class to process the information that need to be done?<br>
  How would you do it?</p>