How to take screen Shot in Ubuntu
Particular window screen shot
Twin view on only one monitor screen shot
There is a program 'shutter' which is a fully featured screen shot application. If you don't have it installed then you should be able to get it by:
$ sudo apt-get install shutter
More simply you will likely have "Take Screeshot" under you Applications—>Accessories menu.
Alt + Print Screen will capture the current window.
By default, the Print Screen (Prt Sc) key on your keyboard takes a screen-shot of the entire screen. You can use Alt + Print Screen to take a screen-shot of the currently active Window.
hit the super-key and type "screenshot" (and hit enter)
than it will open a window and select "Grab the current window" to take a screenshot of a window or select "Select area to grab" to select an area.
hit the "Take Screenshot" button
"Grab the current window" take a screenshot from the last selected window "Select area to grab" to select an area by dragging your mouse (while pressing the left mouse button). save the file or copy it to your clipboard.