yup like the replies prior every sketch is a PApplet
the tutorial for eclipse shows how it works
https://processing.org/tutorials/eclipse/
So i’d guess to have different sketches in a bundle, one could have different sketches (classes) inherited from PApplet and run them in different threads. I’d think they’d have their own windows
and about the threads, i think AWT or more correctly Swing still have something to do with the Event Dispatch Thread which is a java issue. One could nevertheless test to see where the limits are.