Currently I found this feature in acdsee 15 and I definitely like it.
Usually I had to wait while viewer generates thumbnails for every new folder I browse. Most viewers work this way.
Now (wouldn't last long since I use trial version of acdsee) I copy my photos to HDD, run acdsee and force it to rescan my photo folder adding every new image file to the thumbnail database. While the program is working, I can go drink some tea or whatever, even sleep if there's a lot of new files (sometimes there are few thousands of them). Later, while browsing, I do not have to wait for thumbnails to generate and can quickly manage my photos.
With XnViewMP something similar is possible but very inefficient and buggy. It is done via finding all images in this folder and subfolders. Which generates a huge list, and starts creating thumbnails for these pictures... Slow, buggy and forces xnview to waste lot of cpu and ram on creating and maintaining this list.
So, if possible, add feature like 'scan specific folders and index all image files inside them into database'.
Force indexation/thumbgen of specific folders
Moderators: helmut, XnTriq, xnview