Hi,
reproduction;
1.) Use a clean default XnViewMP
2.) Open a .jpg picture in XnViewMP 'view' mode
3.) Under File>Open with go to "Configure programs"
4.) Add an external image editor as a program (I selected Paint.NET)
5.) Make sure that the .jpg picture is still opened in view mode
6.) Now go back to "Open with" and open the file with that same added program
7.) Once opened in the external image editor, do any edits to the picture like adding paint or effects
8.) In XnViewMP, press 'Next' just once to go to the next image file in the directory file list
9.) In external image editor, Save the picture in the image editor and close the editor
10.) In XnViewMP, press 'Previous' just once, to come back to that same edited .jpg picture
11.) Now notice how XnViewMP is only displaying the picture before it was updated, meaning user has to press "reload"
Hmm, so this is not a bug but rather a lack of feature. I believe XnView classic works the same way like this in keeping the original picture in memory.
I think an Auto-reload feature could be added as a tickbox to Settings>General>File operations to control this, so that if enabled it would reload the file within the file list.
Named;- "Automatically reload files on change"