there is a similar/same bug report with ID 3183001, which occurs by running the query against a DB2.

But I can't reproduce this with my Oracle Instances.
Please, answer this questions:
- Which DB did you use?
- How many result tabs are open?
- Did you use scrollable tabbed panes for result tabs? (Global Prefs)
- Did you limit the number of result tabs? (Session Properties - SQL)
- How can we reproduce this?