http://ruexe.blogspot.com/2016/09/ru-518291-beta.html

https://github.com/JamesAmiTw/ru-uefi/

 RU 5.18.291 BETA
This release is mainly for saving snapshot from RU screen as BMP file.  Which is requested by Gary and other users.  Special thanks to Mykhaylo for the help. I didn’t test this version at all, so it could be buggy.  Please leave me a message if you find any bug.

New feature:
RU.EFI: Add F12 key to capture the screen snapshot to BMP file.
File name is auto-generated: Format: “YYYYMMDDhhmmss.bmp”
RU.EXE does not support this.

See post for list of bugfixes.