All,
This relates to Toad for Oracle, Beta 12.12.0.29.
I was editing a query, hitting F2, F5, F9 - I forgot the exact sequence. It’s probably immaterial anyway.
What I first got was an error message like “Out of system resources”
After that I got “Invalid Handle” messages. Lots of them. Trying to close Toad resulted only in more pop-ups with “Invalid Handle”.
I had to resort to the Windows task manager to kill the Toad session 
As a consequence, no information is available in Toad.el. Too bad.
If you would like any additional info, please do ask!