Sprout Forms `onSaveEntry` event I need to add an event handler for the onSaveEntry event in order to integrate with another system. In the admin screens for the form where and how do I add this event handler?
Adding an event handler is not something you do through the control panel.

What you need to do is create a plugin (pluginfactory.io makes this fairly easy), and in your plugin's main class, you have an init() function that looks like this:

public function init()
{
    craft()-&gt;on('sproutForms.onSaveEntry', function (Event $event) {
        $entry = $event-&gt;params['entry']; // fetch the new entry
        ... do things with $entry ...
    });
}


If you structure your plugin properly, you will "do things with $entry" by calling a Service.