If I select a large number of rows (e.g. select * from all_objects) in the code editor, and subsequently export the output (say, to the clipboard), one can - during the fetching of rows - return to the code editor and enter/execute another sql statement (e.g. select * from v$session).
I then get the infamous “SQL Navigator for Oracle has encountered a problem and needs to close. We are sorry for the inconvenience.” dialog…
It would seem that the background-fetch is killed, and the second sql statement gets executed.