There's a reason the "random" option is featured in the slideshow - sometimes you want to browse through images in a non-sequential order. But in slideshow mode, you can only advance on keypress, not go back, and cannot do the usual stuff like copy/move/rate image or any image editing.
It would be nice to have this random order in Browse mode too, i.e. sort thumbnails by random, view an image ctrl-o and go though them in this random order.
Proably this isn't hard to implement, and the slideshow proves it's a useful feature, so I dare to ask
