Do you find your Shutter Screenshot Tool not showing at system tray, and it quits when you close the window? If that so, then perhaps you missed a package when installing Shutter. Just install the missing package and it's done:
sudo apt-get install libgtk2-appindicator-perl
Bonus: if you want to install Shutter with minimal packages download, while having the image editing and tray icon features, just run following command:
sudo apt-get install shutter libgoo-canvas-perl libgtk2-appindicator-perl
Have fun taking screenshots! And thanks Mario Kemper for developing Shutter.