Try this :
1.CREATE TABLE TEST_copy (col1 timestamp);
2.insert into test_copy values(to_timestamp(sysdate));
Then try to copy value from column using ctrl+c not right clicking, and paste into sqlEditor. Value for timestamp sometimes is trimmed to same date, or sometimes some values at the end of value are missing.
Try cliking on cell and copy/paste, an few times the same scenario.