Per the thread title. This currently needs user testing.
To browse your screenshots taken with Power+Y, you only need to enter the 'screenshots' folder; it shows the home directory on your GCW Zero's internal memory by default.
Download: URL o2xiv is now baked into the root filesystem of the GCW Zero firmware, as of 2014-04-27.Sources: https://github.com/Nebuleon/o2xivOriginal sources:
http://sourceforge.net/p/open2x/code/HEAD/tree/trunk/utils/o2xiv/Controls:~In the file chooser~Up/Down: Move selection by one file
L/R shoulder: Move selection by one page
A/B: Select image
Select the '..' entry to go up one directory. The path is displayed on the first line of the screen.
~In the gallery~Start: Options, including Quit
Select: Return to the file browser
X/Y: Zoom in or out
D-pad: Pan (if the image is too large for the screen, including the zoom level making it too large for the screen)
A/B: Rotate clockwise or {counter-clockwise | anti-clockwise}