Bug 460463

SUMMARY: see $SUBJECT

STEPS TO REPRODUCE
1. Detect and recognize a number of faces so Digikam can make suggestions.
2. Start recognition of a number of new photos with a certain person on them (it should keep Digikam busy for ~1min at least to see the issue) 
3. Open the Face view of a person. There should be sufficient faces to make Digikam create a scrollbar for the view, ie. at least 100 or so.
3. Start correcting & reorganizing photos in this face view

OBSERVED RESULT
When a face is detected and Digikam suggests to put it in the currently opened Face view, the scroll position jumps to the top of the view where the suggested face is added, and then back. Sometimes, it does not jump back, or jumps to a completely different position. Also, during detection, selecting faces for reorganization is hard because the input focus keeps flickering.

EXPECTED RESULT
Detecting and/or recognizing faces should not change the foreground view, should not cause flickering of input fields. It should be possible to have a detection job in the background and *simultaneously* reorganize & correct existing faces. Except for the progress bar at the bottom of the screen and the CPU load, face detection and recognition should not be noticeable at all.

SOFTWARE/OS VERSIONS: KDE Neon 20.04 with Digikam-7.9 appimage with debug enabled from 2022-10-12.

Possible duplicate of #402322.