1.3.0: Custom image extensions and/or "Include" back-fordward navigation

[Marsu42]

XnView: MP 1.3.0 - 64 bit
OS: Windows 10 64bit

I'm using an app which uses a custom image extension - .vtx are jpeg files with some custom metadata. I've added this extension to the "include" extension list, but navigation back/fordward (with cursor keys os the mouse wheel) when viewing an image doesn't work.

Effect: To view another .vtx image, it's necessary to close the image and select another image from with "Browser".

To reproduce:
1. Put some jpg files into a folder
2. Rename the extenions to vtx
3. Add vtx to the "Include" extension list
4. Open a vtx image
5. Try to view the previous/next vtx image using back-fordward navigation

Actual behaviour (bug): back-forward navigation is impossible, the Viewer is stuck on the current image

Expected behaviour: back-fordward navigation moves the Viewer to the previous or next .vtx image, like it's with .jpg

=> A solution might be be to enable custom extensions for images (it's only possible for Audio/Video/...) if this fixes navigation.

[masterjp]

I can confirm this wrong behaviour of XnViewMP.

[xnview]

'include' can't be used for that. Try to disable 'Settings>File list>Recognize only by extension'?

[Marsu42]

'include' can't be used for that. Try to disable 'Settings>File list>Recognize only by extension'?

I've disabled "Recognize only by extension" and the .vtx files (i.e. every extension which is an image) show up without adding the extension to the include list.

However, back-fordward navigation with the mouse or keys is still broken, the image viewer is still stuck on the same image.

Any solution would be very welcome - I guess disabling "Recognize only by extension" probably slows down scanning, and I'm wondering what the "Include" filter is for if not for including extensions