If you are interested in just the current window, not the entire
desktop, use Alt-Print Screen.

The only problem that I have with this is that it creates a 256 color
bitmap, probably because my desktop uses 256 colors, although I have not
tested changing it to just 16. The software itself that I need to 'grab'
shots of really only uses 16 colors, which result in a graphic of about
half the size of the same screen at 256 colors. The easy solution might
be to reset to just 16 colors, which I am unwilling to do for the
occasional shot, but might be ideal for someone spending much of their
time documenting software. What I do is paste into paint, then Save As
type: 16 color, reselect, recopy, and then paste into my email or
document, cutting down on the bulk.

I have yet to need to get software for this need.
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