The event editor popup is completely custom code in Sampler. Unfortunately, it does not show the source code for that.
Essentially, it catches event clicks with a EventClickHandler, opens the editor form in a Window, and then updates the event according to the data. I’d guess the event editor takes around 50-100 lines or so.
Thank you very much for your ansewer i finally resolved the issue by creatin my own class MyCustomBasicEvent that extends BasicEvent and i added attributes to it and it works good .
Thank you very much