Image browser - show custom files as thumbnails

[Dreamer]

In "thumbnails" view (image browser) non-image files cannot be shown, option to show also non-image file would be nice.

I see now that it's possible to show also non-image files by disabling all formats in Preferences > Image browser, but it's not clear.

I suggest to add also other extensions, perhaps also custom extension. Also such a buttons would be nice:

[x] images | [x] video files | [ ] archive files | [ ] all others