I just reproduced it with the following steps. I don't know if each of the steps is necessary, but it's just what I attempted in my first reproduce attempt:
1) Start SlickEdit 22.0.2 with new configuration (vs +new -sc junk)
2) Cancel config wizard, open options, and change the following Backup options
-- set Backup directory path to a directory under my Windows TMP dir
-- set Number of backups to keep for each file to 20
-- set Limit size of backup to off
3) Open Backup History tool window
4) Create a new file, enter some text, and save (Ctrl-S)
5) Repeat 20 times -- modify file, and resave. At the end I had versions 20 through 1 in the backup history.
6) Close the file, then close SlickEdit.
7) Start beta 6 (haven't installed rc1 yet) with the same new config directory.
Open the test file, modify it and save.
At that point, I did not see an updated entry in the Backup History window.
9) Open Options, change Limit backup size to On, Apply, change back to Off, and select OK to save/dismiss options dialog.
10) Modify the test file one more time and save.
At this point, I now get version 21 in Backup History.
I'm running on Windows 10 Enterprise (x64). TMP dir and file I edited are on C: drive (NTFS).
