Pressing the <backspace> key sequences backwards through an alphanumerically-sorted list of all supported image-file types (JPS,DAS,BMI,JPG,STJ,BMP,TIF) in the most recently selected folder
(e.g. the folder that may have been used with 'File/Open Stereo Image') and displays them using the currently-selected stereo-format.

Alternatively, if the image-width does not exceed the window-width, you may click the left-side of an image or image-pair.

If the image-height does not exceed the window-height, you may also click near the bottom of an image or image-pair.

On reaching the first image, the sequence continues at the last image.