You are quite correct Cadcam, except that print screen gets you
everything on the screen which requires cropping the pic down afterwards, which I haven't figured out how to do. If I can't figure out how to do something in a minute or two of snooping around in help, then it's too much trouble for me.
Also, Onecnc's output is in png format, which is extremely compact compared to bitmap formats which Paint gives you.
It was kind of funny, because I was composing a long letter to Onecnc support, in which I was going to suggest exactly what they have already done