I have to take a Screen-shot icon from left favorite bar to open a Copy to clipboard ----------- save window. When I was using ctrl + Alt + print shortcut in setting in the All Systems -> Keyboard, the window never show and the Picture directory have nothing.
I'm not sure I understand the question, but if you are looking for the screen-shot shortcut its just PrtSc on your keyboard. Just press the button and gnome-screen-shot will open and ask you where to store the screen-shot.
If you want more advanced screen-shot options open Software Center and search for "shutter".