To install Shutter on Ubuntu Linux with working screenshot editing extension, you must execute the following command. It will install the required packages via the Ubuntu package manager, which are needed for the screenshot editing extension.
sudo apt install shutter libgoo-canvas-perl gnome-web-photo
In Ubuntu 18.04 the libgoo-canvas-perl package is missing. Here is an article, which is describing the fix for this: http://ubuntuhandbook.org/index.php/2018/04/fix-edit-option-disabled-shutter-ubuntu-18-04/.
Then "restart" your computer. Afterwards Shutter looks like in the attached screenshot. Of course it will be in your operating system language. Mine is German.
Happy screen photographing! (: