Enhance "Create thumbnails --> Render" to force thumbnail (re)creation.

[jefferysmall]

Setup (please complete the following information):

• Xubuntu 22.04.4
• Geeqie 1.7+git20220327-6d541232

Describe the bug
I've reported a number of other issues with thumbnails not updating properly when image files in a directory are renamed quickly in groups. I don't know if this will ever be addresses, so I want to be able to manually force the recreation of all thumbnails in a directory to get them in alignment with the images. I thought that:

Cache Maintenance --> Create thumbnails --> Render

would do this, but apparently if a thumbnail already exists, it just passes over the file. I need this command to be modified , or a parallel one created, that will force the thumbnails for all files in a specified directory to be recreated from scratch so that the mismatch thumbnails get synced with the actual file image.

Screenshots
Here's an example. I have a file with about a thousand symbolic links to files in other locations. These are pictures I load onto a card for display on a digital picture frame. When I add new links to this list I then run a custom command that randomizes all the link names so that the same link names end up pointing so some other random image file. The links are renamed quickly and Geeqie currently is incapable of recognizing that something has changes so that, in many cases, the old thumbnail associated with that link name is retained. (BTW, the same thing happens in folders containing the actual files which get renamed, so this isn't a symlink problem.) See attached screenshot. image_0746.jpg shows the sunset, but the thumbnail still shows the buffalo head that used to be assigned to this "image_0746.jpg" name.

[caclark]

If you press R to refresh, does the thumbnail get updated?
If you touch the file then refresh, is the thumbnail updated?