In Dos command to take screenshot, you can use (see https://developers.google.com/web/updates/2017/04/headless-chrome):
chrome --screenshot="C:\test\test.png" "http://google.com" --headless --disable-gpu
In Rebol, I can make it work only using powershell -command:
call {powershell -command "chrome --screenshot='C:\\test\\test.png' 'http://google.com' --headless --disable-gpu"}
In red I cannot make it work at all, did I miss something ?
This one works with the newest build, if you use the full path
>> call "C:\Program Files (x86)\Google\Chrome\Application\chrome.exe --screenshot=c:\test\test.png https://www.google.com --headless --disable-gpu"
== 1932