@davidfor: In some (most?) cases, letting Nickel handle the processing may also be highly unwanted behavior, if you care about quality

(and
I do ^^).
Granted, in KFMon's case, we don't care, because we'll probably never see those thumbnails used as screensavers, so the autogenerated ones are good enough

.
EDIT: And, again in KFMon's case, when you delete a "watched" icon, KFMon will detect that (straight away), and abort, so you'll probably want to reboot an one point anyway to get KFMon back up

.
Code:
[KFMon] [2018-07-12 @ 16:37:57] [NOTE] Tripped IN_IGNORED for /mnt/onboard/kfmon.png
[KFMon] [2018-07-12 @ 16:37:57] [INFO] Trying to remove inotify watch for '/mnt/onboard/koreader.png' @ index 0.
[KFMon] [2018-07-12 @ 16:37:57] [INFO] Trying to remove inotify watch for '/mnt/onboard/icons/plato.png' @ index 1.
[KFMon] [2018-07-12 @ 16:37:57] [INFO] Stopped listening for events.
[KFMon] [2018-07-12 @ 16:37:57] [INFO] Beginning the main loop.
[KFMon] [2018-07-12 @ 16:37:57] [INFO] Initializing inotify.
[KFMon] [2018-07-12 @ 16:37:57] [NOTE] Setup an inotify watch for '/mnt/onboard/koreader.png' @ index 0.
[KFMon] [2018-07-12 @ 16:37:57] [NOTE] Setup an inotify watch for '/mnt/onboard/icons/plato.png' @ index 1.
[KFMon] [CRIT] inotify_add_watch: No such file or directory
[KFMon] [2018-07-12 @ 16:37:57] [ERR!] Cannot watch '/mnt/onboard/kfmon.png', aborting!