There is a trick for doing that, actually. Dunno if you are on a mac or PC, but take a screencap of the window or screen, and paste it into a file. You can save it and save your picture. If you want to cut it out.. There’s ways of doing that anywhere.

For WINDOWS, you can easily press the “Print Screen” (also called Prt Scn, Prnt Scrn, Prt Src, etc) key, open MSPaint, and paste it in (either press Ctrl+V or go to the Paste function in one of the menus).