Alt-C not working in Properties dialog to select Octal field

Using version 5.15.1 (build 9047) on Windows 7.

Steps to reproduce:
- Log into a site
- Highlight a remote file and press F9
- When Properties dialog appears press Alt-C. Nothing happens.
- Try Alt-o and the Owner 'R' field is highlighted.
- Try Alt-g and the Group 'R' field is now highlighted.
- Try Alt-h and the Owner 'R' field is now highlighted.

This used to work but I cannot remember what version that was.

Thanks for your report.

This issue has been added to the tracker:
https://winscp.net/tracker/1743