A command-line screenshot maker.
http://rammichael.com/a-command-line-screenshot-maker

Based on:
https://blog.mozilla.org/ted/2009/02/05/command-line-screenshot-tool-for-windows/

To build with GCC/MingW32 run a command like this:
g++ -O3 'Screenshot Maker.cpp' -s -static -o screenshot.exe -municode -lgdi32 -lgdiplus