[vprcic]

This was my intention as well so I tried familiarizing myself with PlantUML code (made a small contribution as a result), but in the end, I came to the conclusion that the overhead of getting to know its ins and outs would be greater than to get a new project to a usable state from scratch. PlantUML is, unfortunately, burdened with years of development choices that make it tough to modify in a way to conform to what I need. Most of these functionalities were (I'm 100% sure for the multiple threads and customization of the visuals), at some point, mentioned in various forum discussions as "possibly under development" by the developer, just to be followed with years of silence on the topic. And if they aren't able to deliver those, I'm not going to be, for sure.