Can you reproduce this? In Lazarus, execute this key sequence:
F11, Ctrl+Tab, Tab, o, n, k
Then this exception is raised:
Lazarus IDE v1.9.0 - project1
List index (-1) out of bounds.
Press OK to ignore and risk data corruption.
Press Abort to kill the program.
Version doesn't matter, I believe this exists for a very long time,
although I have fairly fresh version, several days old.
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