You can also use the
gnome-panel-screenshot command in a terminal (of course, a different one), by dropping the
-w) parameter, which will allow you to grab a window instead of the entire screen.
The command should look like:
gnome-panel-screenshot --window --delay=10
gnome-panel-screenshot -w -d 10
--delay=10 and the
-d 10 parameters will give you 10 seconds in order to choose the appropriate window of which you wish a screenshot. Change this value in order to adjust it to your needs.
If you wish a screenshot of the current terminal window simply drop the
gnome-panel-screenshot -window or
gnome-panel-screenshot -w without any other parameters, for the whole screen drop no parameters at all.
For a guided screenshot grabbing simply drop the
gnome-panel-screenshot -i command in a terminal which will produce this window:
BTW: You don't need to drop this last one in a terminal, simply hit the AltF2 keys and enter it in the "Run application" dialog window. After which you can choose whatever options that better fits your needs for screen-shooting.