When running a groovy script from the editor (launched with "RUN" button), it blocks the UI until the script has finished/terminated.
If the script takes a long time, it leads to a session timeout (indicated by that red box).
It would be nice to have the possibility use other apps (whatever) during the script runs.
The combination of blocked UI and (possible) timeout might be confusing for users, since the don't know whether the script really has finished successfully (since the mini groovy console cannot display anything after a timeout).
Interesting read before tackling this issue https://vaadin.com/wiki/-/wiki/Main/Using+server+initiated+events