This is Viewnior, an image viewer program. Created to be simple, fast and elegant. It's minimalistic interface provides more screenspace for your images. Among its features are:

* Fullscreen & Slideshow
* Rotate, flip, crop, save, delete images
* Animation support
* Browse only selected images
* Navigation window
* Set image as wallpaper (only under GNOME, see INSTALL file)
* Simple interface
* Configurable mouse actions