Hi,
I've just released retro2png; a utility to take snapshots of the Raspberry Pi screen using gamepad, mouse and/or keyboard hotkeys in RetroPie, Sneses/Blast16, X11, ssh, the command line, in most running games and apps etc.:
https://github.com/Vegz78/retro2png
retro2png is a fork of the pioneering and much better known raspi2png from @AndrewFromMelbourne, with the following new modifications/features that I found useful on my RetroPie setup:
-Automated install scripts for Raspbian/RetroPie and Blast16/Sneses etc. which includes and sets up Triggerhappy hotkeys
-Saves default to the "~/Pictures" folder when run with just retro2png without any command line parameters
-Triggered by keyboard, mouse and/or game controller hotkey combinations, as well as from the command line/ssh
-Up to 99 auto-incremented standard "retro2png_X.png" file names in all specified save folders
-Save folder easily specified anywhere behind the retro2png command without need of flags, or together with other flags
-Keyboard, mouse and/or game controller hotkeys are fully and easily configurable, works from most applications and user interfaces and can be used inside Recalbox/games for other functionality/apps than just retro2png screenshots
I know that Recalbox already has at least 2 convenient screenshot alternatives built-in, but retro2png might add extra screenshot and hotkey functionality desired by some users of Recalbox.
retro2png should also work in Recalbox and I hope this utility can be useful for some of you as well! Tests and feedbacks on how it works(or not) are most welcome. 
Br,
Vegard
