Linux: wrong sequence when photos added by external program

[rmtk]

For instance, there is a folder in Xnview MP browser containing photos 2.jpg, 3.jpg, 4.jpg, ...
You open 3.jpg in Xnview MP viewer, and then add a new photo 1.jpg into the folder using your file manager.
Now click the "previous file" button in viewer, you will see 1.jpg instead of 2.jpg, or click the "next file" button still to see 3.jpg instead of 4.jpg.

I'm using Xnview MP 0.64 64bit on Linuxmint 16 with Mate desktop. This bug does not exist on windows version.