Capture Screen
Opens a new window with a capture of your screen.
The shortcut (Ctrl+Maj+X) is very usefull, because it avoids the mouse to be moved when you do the capture.
Note that it is impossible to capture a screen with an opened menu. Even you are click of the Capture Screen button, the menu closes before making the screen.
NB : the picture is not automatically saved. (You can do it with the save/save as button.)
Example of saved screen : 
