Because our main developer started as dedicated PHP developer in his journey with VtigerCRM, which complain about not having any chance to modify existing functions, he always take a look to implement lot’s of interfaces into our modules. So you have many ways to add additional functions.
If you are a PHP developer you could extend the Workflow Designer over lot’s of interfaces.
I implement lot’s of these interfaces only for the VT 6+ version. If you are still using 5.4, you probably don’t found the directories I describe here.
The most important fact for your should be: Don’t modify any files originally created by the core Workflow Designer.
Like in any modules from Redoo Networks, interfaces are stored in the extends extends of Workflow Designer.
I started to outsource lot’s of Workflow Designer core functions also into such “Extensions” and not implement everything into the module itself.
Because everything within the extends directory is unencrypted you have the chance, to modify them by your needs.