Then klicking on "next file" will show the file after the next (new!) file (pict.jpg), but the title of the picture in the headline ist the title of the next (new) file (pic_m.jpg). If I modify this file (pict.jpg) too and save it with the suggested filename, the modified file (pic-m.jpg) will be overwritten.
I took some screenshots.




After saving the modified file with a new name, the filename in the headline should be changed to the new name.