Feature: #70531 - RequireJS module for split buttons 

Description 

A RequireJS module for split buttons has been added. The module can be used in another RequireJS modules to add callbacks being executed before the submit takes place. As the callback receives the click event, the submit can be modified, e.g aborting the submit.

Impact 

To use the SplitButtons module, include it in your own RequireJS module:

define('Vendor/Ext/Module', ['TYPO3/CMS/Backend/SplitButtons'], function(SplitButtons) {
	// Your code...
});

Callbacks will be added by calling SplitButtons.addPreSubmitCallback:

SplitButtons.addPreSubmitCallback(function(e) {
	// Code being executed as callback before submit
});