If you search "Screenshot" in the DASH you will see two options "Screenshot" and "Screenshot capture toolbar"
"Screenshot capture toolbar" is part of SMART Notebook Software and should only be used in conjunction with that software.
This is an incredibly useful tool. Full screen, window and selected area are all options as well as timing the screenshot will allow you to open menus. The result is a PNG file you can use or edit with Shotwell or GIMP.