While writing documentation and howtos, i prefer to take screenshots for every tasks where words are just too much. Sometimes i’ll edit them with gimp, but for the most common scenario a simple tool will to do the trick.
Press ‘Print’ or ‘Alt + Print’ for the current window using gnome-screenshot. For the more advanced solution, install shutter.
# apt-get install shutter
You may then select areas and edit the taken screenshots before saving them elsewhere.